Department of Defense

IMT-2000

Technical Working Group

Interim Report

Investigation of the Technical

Feasibility of Accommodating the

International Mobile Telecommunications

(IMT) 2000

Within the 1755 – 1850 MHz Band

27 October 2000

IMT-2000 Assessment

i

EXECUTIVE SUMMARY

Advances in wireless and digital technologies have led to the development of Third Generation (3G)

mobile wireless services, sometimes referred to as International Mobile Telecommunications for the

Year 2000 (IMT-2000). Recently, the World Radiocommunication Conference 2000 (WRC-2000)

identified several frequency bands that administrations are urged to considered when developing IMT-

2000 mobile services. The frequency bands identified by WRC-2000 to support additional mobile

services include 698-960 MHz, 1710-1885 MHz, and 2500-2690 MHz.

The United States is seeking to develop IMT-2000 services as rapidly as possible. In the US, interest in

IMT-2000 has focused on the two higher frequency bands for further study. In the frequency band

1710-1885 MHz, 1755-1850 MHz is allocated to Government Fixed and Mobile Services. Without

question the largest single user of the band is the Department of Defense (DoD). This report presents

the interim results of the technical assessment of sharing or segmenting the 1755-1850 MHz band with

IMT-2000 and its implications to major DoD systems. The final report will assess the critical

operational and cost implications of accommodation of IMT-2000 in the 1755-1850 MHz band. Use of

the 2500-2690 MHz frequency band is managed by the Federal Communications Commission (FCC).

The 1755-1850 MHz frequency band supports a wide variety of DoD systems crucial to the warfighter’s

ability to successfully perform missions. Although the DoD has over one hundred nomenclatured

systems that employ this spectrum, this interim assessment addresses only selected major systems. The

major functions supported include tracking, telemetry, and commanding (TT&C) of DoD space systems,

transportable tactical radio relay communications, air combat training, fixed radio relay

communications, and mobile video control links. Specific systems include, but are not limited to, the

Space Ground Link Subsystem (SGLS) which provides space systems TT&C, Mobile Subscriber

Equipment (MSE) and Digital Wideband Transmission System (DWTS) which support tactical

communications, and the Air Combat Training Systems (ACTS) and the Joint Tactical Combat Training

System (JTCTS) used to support air combat training.

The DoD has formed three working groups, Technical, Operational, and Cost, to assess the impact of

proposals to reallocate 1755-1850 MHz to shared or non-government operation. While the working

groups are performing in close coordination, the initial assessments are being made primarily by the

Technical Working Group (TWG). This report documents an electromagnetic compatibility (EMC)

assessment of only selected major DoD systems and possible IMT-2000 systems. Schedule limitations

prevented detailed consideration of all DoD systems; however, certain critical DoD systems were

IMT-2000 Assessment

ii

addressed. Many IMT-2000 technical parameters are yet to be finalized; consequently, notional IMT-

2000 parameters were coordinated with the FCC and were used in the assessment.

The limited EMC assessment considered two-way interactions between candidate IMT-2000 systems

and SGLS, tactical radio relay systems, air combat training systems, and tactical weapons control

systems. Full band sharing was considered, as were possible band segmentation plans. This report

documents the following possible sharing options:

• Full band sharing of the 1755-1850 MHz spectrum

• Band segmentation: 1755-1805 MHz retained for Federal Government use, 1805-1855 MHzreallocated for commercial use

• Phased band sharing: IMT-2000 phased over 1755-1790 MHz, with restrictions on IMT-2000systems

The results of the full band sharing EMC assessment indicates that significant undesired interactions

may occur both to and from DoD systems. Distance separations needed to preclude interference can be

substantial, particularly in the case of airborne platforms. SGLS receivers represent a particular

problem, as aggregate IMT-2000 emissions may quickly degrade needed link margins.

Band segmentation plans as a means of sharing produced mixed results. Reallocation of

1805-1855 MHz to non-government services may have a major impact on systems performance yet to

be determined, although in some cases it appears technically feasible. Phased band sharing with

coordination requirements and operational restrictions on IMT-2000 systems seems theoretically viable

from the DoD perspective for most DoD systems, but may not be operationally acceptable to the

IMT-2000 community. However, for the SGLS receivers this option will quickly become problematic.

These results are based solely on the technical assessment. This effort only analyzed the interactions

between one DoD system in operation at any given time on a one-to-one basis with IMT-2000 systems.

In order to determine the full possibility of sharing, operational impacts must be determined. Further,

DoD operational risks associated with any band segmentation approach must be assessed to determine if

band segmentation will enable DoD to conduct operations in a satisfactory manner. Operational and

cost risks associated with undesired interactions will be assessed in the next phase of the DoD

assessment.

Some possible means to mitigate potential interference were identified and are presented in the report.

In some cases mitigation measures would be applied to either IMT-2000 systems or to DoD systems. In

other cases cooperative measures would be necessary. In all cases, the operational risks associated with

each possible mitigation measure will have to be addressed in the next phase of the DoD assessment.

IMT-2000 Assessment

1-1

1.0 INTRODUCTION

1.1 BACKGROUND

In recent years mobile wireless telecommunications systems have experienced a growth that is matched

by few other technologies. Large-scale mobile wireless common carrier services began with cellular

systems, sometimes referred to as first-generation systems. Subsequently, second-generation systems,

Personal Communications Services (PCS), provided many enhancements to cellular-type service.

Advances in several technologies have led to the development of third-generation (3G) services,

sometimes referred to as International Mobile Telecommunications for the Year 2000 (IMT-2000).

Recently, the World Radiocommunication Conference 2000 (WRC-2000) identified several frequency

bands that administrations are urged to consider when developing additional mobile services.

Identifying common frequency bands will enhance economies of scale and promote universal mobile

telecommunications services.

The frequency bands identified by WRC-2000 to support additional advanced mobile communication

services include 698-960 MHz, 1710-1885 MHz, and 2500-2690 MHz. In the US, study is required on

the two higher frequency bands. In the 1710-1885 MHz frequency band, 1755-1850 MHz is allocated to

Government Fixed and Mobile Services. Many Federal Departments make substantial use of the 1755-

1850 MHz frequency range for fixed and mobile operations. Without question, the largest single user of

the band is the Department of Defense (DoD).

For the DoD, 1755-1850 MHz supports a variety of large and critical systems, as well as many

important, long-established local users and systems in development. The major functions supported in

the band include tracking, telemetry, and commanding (TT&C) of DoD space systems, transportable

tactical radio relay communications, air combat training, fixed radio relay communications, and mobile

video control links. Specific systems include, but are not limited to, the Space Ground Link Subsystem

(SGLS) which provides satellite TT&C, Mobile Subscriber Equipment (MSE) and the Digital Wideband

Transmission System (DWTS) which support tactical communications, and the Air Combat Training

Systems (ACTS) and the Joint Tactical Combat Training System (JTCTS) used to support air combat

training.

Federal Departments have been asked to examine their use of the 1755-1850 MHz frequency band and

to assess the prospects for sharing spectrum with IMT-2000 systems. The DoD is complying with this

request by identifying all DoD systems that operate in the band of interest, assessing the technical

feasibility of sharing, examining the operational impact of sharing and/or relocation, and quantifying

IMT-2000 Assessment

1-2

cost issues associated with sharing and/or relocation. This interim report presents an initial assessment

of the technical issues associated with sharing by examining electromagnetic compatibility (EMC)

issues associated with selected DoD systems and several candidate IMT-2000 systems. While IMT-

2000 services will ultimately be deployed worldwide, the focus of this effort was primarily sharing

issues in the US. Further technical assessments and discussions of operational and cost issues will be

presented in subsequent reports.

1.2 OBJECTIVE

The objective of this effort was to perform an initial assessment of the technical feasibility of sharing

and identify EMC issues between possible IMT-2000 mobile wireless systems and selected DoD

systems that operate in the 1755-1850 MHz frequency band. This study is designed to be a part of a

larger effort involving separate operational and cost analyses.

1.3 APPROACH

The overall approach to this task was fundamentally similar to the basic approach used in standard EMC

assessments. Technical parameters for the radio frequency (RF) systems were identified, possible

operational scenarios were defined, desired and interfering signal levels were predicted at the receivers

of interest, and predictions were made with respect to the potential for undesired interactions. If

undesired interactions were predicted, then required distance and/or frequency separations to avoid

interference were calculated. Also, in those cases where interference was predicted, possible means to

mitigate interference, beyond frequency/distance separations, were identified. Unique aspects of

individual interactions are discussed in the individual assessments.

Specific technical parameters of IMT-2000 systems were required for the EMC assessments. However,

at the time this assessment was performed, IMT-2000 hardware was not in production for the US

market. Consequently, it was necessary to develop parameters from the technical literature, to consider

selected aspects of existing wireless mobile systems, and to calculate certain characteristics using

communications theory. The basis for the final parameters used in the assessments was a Federal

Communications Commission (FCC) document presenting notional characteristics for the various

technologies that may be used to implement IMT-2000. Minor modifications to some of the FCC-

postulated parameters were made following discussions between staff supporting the FCC and technical

staff supporting the DoD EMC assessment effort. The IMT-2000 technical parameters are presented in

some detail in the Analysis section.

IMT-2000 Assessment

1-3

The DoD performed an extensive survey of operational commands, program offices, support facilities,

and acquisition documentation to identify RF systems that operate in some or all of the 1755-1850 MHz

band. Several hundred systems were identified, and basic information on these systems was compiled

for use in this study. Individual EMC assessments of all of the DoD systems was not possible within the

available time. For this initial effort several major critical systems were selected for EMC assessments

to scope the extent of interference issues, to initiate a dialogue between government and industry

regarding sharing options, and to begin examining possible interference mitigation measures. The DoD

systems addressed in this report are the SGLS, transportable tactical radio relay radios, ACTS, JTCTS,

and several precision strike weapons. EMC assessments of additional DoD systems will proceed

following the completion of this interim effort.

For the DoD systems considered, extensive technical and operational data was gathered. This

information included system waveforms, transmitter parameters, system losses, antenna patterns,

antenna pointing angles, siting data, receiver selectivities, and receiver performance criteria. In addition

such operational information as geographical locations, link lengths, and aircraft altitudes was also

gathered. Planned system upgrades were considered when available technical data was sufficient to

support an EMC assessment.

Having gathered notional technical data on IMT-2000 systems and actual data on DoD systems, analysts

assessed the technical feasibility of sharing in the 1755-1850 MHz band. Several sharing scenarios were

considered, and the assessment sharing scenarios were conducted based on the interference analysis

between systems on a one-to-one basis, and no consideration was given to interactions among multiple

systems. In the first scenario, complete frequency sharing of the band was considered; that is, it was

assumed that IMT-2000 systems could operate anywhere in the band, and DoD systems would operate

as they do now. Also, two band segmentation plans were considered. In the first segmentation plan,

1805-1850 MHz was hypothetically reallocated to non-government use, and 1755-1805 MHz remained

available for operation of government systems. In the second plan, phased sharing occurs where

1710-1755 MHz would be available for IMT-2000 immediately, and as network capacity required,

1755-1780 MHz would become available at a future date, followed by 1780-1790 MHz. In this second

segmentation plan the spectrum in the band of interest would be available only for mobile-to-base links,

and IMT-2000 operations within coordinated distances of relevant DoD sites would use a listen-before-

transmit capability to manage frequency usage to avoid interference. Additional band segmentation

plans and possible relocation options will be addressed in future efforts from an operational, cost, and

technical viewpoint.

IMT-2000 Assessment

1-4

It should be noted that the technical assessments documented in this report used material presented in

International Telecommunication Union (ITU) documents, documents from the European

Telecommunication Standards Institute (ETSI), previous Joint Spectrum Center (JSC) reports, and other

technical sources. Reference material is cited as appropriate throughout this report.

The main body of this report provides background material on the sharing issue, system descriptions of

the IMT-2000 and DoD equipment considered in this initial assessment, a description of the technical

approach, an identification of critical assumptions applicable to all of the technical assessments, and a

discussion of the results. There are several appendixes to this document. Each appendix provides a

detailed description of the DoD system(s) considered in that appendix, a description of the specific

technical approach used in the associated assessment, an identification of critical assumptions made in

order to complete the technical assessment, and a discussion of the results of the assessment.

IMT-2000 Assessment

2-1

2.0 SYSTEM DESCRIPTIONS

2.1 IMT-2000 SYSTEM DESCRIPTION

IMT-2000 and 3G services are the names commonly used to refer to the next-generation mobile wireless

telecommunications services. The 3G family of services, and the systems that will provide them, are

intended to reflect a high degree of commonality and are to be compatible with each other. These

services will support mobile and fixed users employing a wide range of devices including small pocket

terminals, handheld telephones, laptop computers, and fixed-receiver equipment. 3G services are

envisioned to be ubiquitous throughout the globe, as available in a remote part of a developing country

as they are in an urban area in a highly developed country. Seamless roaming is a key attribute. Access

to services is expected to be uniform. Furthermore, the user will be able to roam from an urban setting

to a suburban one into a rural setting without loss of basic services.

Consumer demand for services available at any place, coupled with the expectation of high quality, are

key drivers in the effort to establish commonality and compatibility of 3G terrestrial telecommunication

systems. It is estimated that by the year 2010 there will be one billion wireless subscribers worldwide

on 3G networks.1 At the present time, the worldwide penetration of wireless service is approximately

7½ percent and it is expected to exceed 30 percent by the end of the first decade of the new millennium.2

There are over 1,300 cellular and second-generation terrestrial mobile service networks currently

operating worldwide, each with a limited geographic coverage. Hence, it is easy to understand the

importance of standardization in system design and service provision for 3G services if uniform services

and seamless roaming are to be provided on a regional or global scale.

It is generally agreed that IMT-2000, or 3G, systems will require use of spectrum that extends beyond

that already encumbered by first and second generation mobile systems. A major issue in the global

debate regarding 3G system design, standards, and services that must be resolved is the amount of

common or “harmonized” spectrum that will be available on a global and regional basis to support 3G

systems. For ease in roaming, to help stimulate commonality in services, and economies of scale,

proponents of 3G services believe it is important to identify as much contiguous harmonized spectrum to

support worldwide 3G operations as is practical. This will stimulate the development of global and

regional coverage of 3G systems by reducing the cost and complexity for system development, thus

1 United States Talking Points for WRC 2000 on IMT–2000 spectrum requirements.

2 Id.

IMT-2000 Assessment

2-2

providing users with more cost-effective services. The ITU, with the support of the US, has designated

1710-1885 MHz as a frequency band suitable for the development of IMT-2000 services. The technical

parameters of the IMT-2000 system used in the assessment are contained in Appendix A.

2.2 DOD SYSTEM DESCRIPTIONS

The DoD has received spectrum certification for hundreds of communications-electronics systems in the

1755-1850 MHz frequency range and operates many thousands of these systems in the US and abroad.

Each of the military services has major, critical systems in this frequency band, as well as important

local systems for command and control, security, telemetry, target scoring, video links, and a variety of

other functions. Table 2-1 identifies some of these systems and the functions the systems perform.

Table 2-1. Examples of DoD Systems Operating in 1755-1850 MHzSystem Name Function

Space Ground Link Subsystem Satellite telemetry, tracking, and command

AN/GRC-103 Tactical radio relay

AN/GRC-226 Tactical radio relay

AN/GRC-245 Tactical radio relay

AN/MRC-142 Tactical radio relay

AN/SRC-57 Tactical radio relay

Tactical Aircrew Combat Training System Air combat training

Air Combat Maneuvering Instrumentation System Air combat training

Joint Tactical Combat Training Systems Air combat training

Weapons Control Link Control of precision strike weapons

Land Warrior Wireless local area network for combat troops

AN/DSQ-37 Target scoring system

Combat ID for the Dismounted Soldier Tactical communications

Intrusion Detection System Perimeter security

Robotics Control System Wireless remote control

Within the time and resources available for this assessment it was not possible to address all of the DoD

systems certified to operate in 1755-1850 MHz. Several critical systems were selected for the

assessments to help establish the scope of compatibility issues associated with the possible sharing of

the frequency band. Overviews of these systems are provided below. Detailed descriptions and the

technical parameters used in the assessments are presented in the associated appendix.

IMT-2000 Assessment

2-3

2.2.1 Space Ground Link Subsystem

The DoD conducts satellite operations (SATOPS) in the 1755-1850 MHz and 2200-2290 MHz

frequency bands to maintain control of, and to receive health and status data on, over 120 satellites

flying in both geostationary and non-geostationary orbits. The DoD SATOPS uplink functions, which

include the transmission of commanding and ranging signals, are performed in the 1761-1842 MHz

portion of the band. Downlink telemetry data is passed via the 2200-2290 MHz band. The Air Force

Satellite Control Network (AFSCN) is a worldwide network of US Air Force ground stations and

control centers which provide telemetry, tracking, and commanding (TT&C) services to DoD satellites.

The AFSCN consists of two control nodes, Schriever Air Force Base, CO, and Onizuka Air Station

(OAS) at Sunnyvale, CA, plus eight Automated Remote Tracking Stations (ARTS) dispersed both

within and outside the US. The earth stations generally employ high-power transmitters with highly

directional, tracking antennas capable of pointing to within three degrees of the horizon. The

spaceborne systems use very sensitive receivers with omnidirectional antennas.

A description of SGLS spaceborne receiver operations and the associated assessment of potential

interference from IMT-2000 emitters are presented in Appendix B. A description of the SGLS earth

station transmitters and the associated assessment of potential interference to IMT-2000 receivers are

presented in Appendix C.

2.2.2 Tactical Radio Relay

Mobile Subscriber Equipment (MSE). The MSE is a multi-band, tactical line-of-sight (LOS) radio

system, more accurately described as a “system-of-systems,” because it is composed of several

components, each of which are fully operational systems. The individual components that make up the

MSE are dependent upon several portions of the radio frequency spectrum. The inability of any of these

components to operate successfully would result in the failure of the overall system. One critical

component of the MSE, the AN/GRC–226(V)2 radio, operates in the 1755–1850 MHz frequency band.

It is used to connect radio access units to the node center switch of the network. Operational use plans

call for 465 units per Army Corps, giving a total of 2,325 units for five Corps. The AN/GRC-226(V)2 is

a digital radio that can tune to any of 4000 available channels, spaced at 125 kHz, between

1350-1850 MHz; however, due to the allocation of most of this band to other services, users rarely have

access to spectrum outside of 1350-1390 MHz and 1710-1850 MHz. The AN/GRC-226(V)2 requires a

50.125-MHz minimum frequency separation between transmitter and receiver for a duplex link.

IMT-2000 Assessment

2-4

High Capacity LOS (HCLOS). The HCLOS is expected to eventually replace the AN/GRC-226(V)2

radios in the MSE for the Area Common User System (ACUS). The HCLOS radio, the AN/GRC-

245(V) operates with increased spectral efficiency and higher data rates compared to the current radio.

The AN/GRC-245(V) requires a 50.125-MHz minimum frequency separation between transmitter and

receiver for a duplex link.

Digital Wideband Transmission System (DWTS). The DWTS consists of two components, the shore

based USMC AN/MRC-142 and the ship based US Navy AN/SRC-57. DWTS is an LOS tactical radio

system providing point-to-point (shore based AN/MRC-142), ship-to-ship (ship based AN/SRC-57), and

ship-to-shore (AN/MRC-142 and AN/SRC-57) communications. The DWTS provides communications

vital to the Commander Joint Task Force (CJTF), Commander Amphibious Task Force (CATF),

Commander Landing Force (CLF), Amphibious Forces afloat, and US Forces ashore. The system

provides afloat and ashore commanders with entry into the Global Command and Control System –

Maritime (GCCS-M) to ensure common access to intelligence, mapping, order of battle, and logistics

information. The DWTS provides data transmissions for Battlegroup (BG) planning, video tele-

conferences, BG e-mail connectivity, Internet connectivity, and intra-BG telephone connectivity.

DWTS provides tactical digital wideband transmissions for voice, video, and data to support landing

force command elements to include Marine regiment or Expeditionary Unit and higher and Army

brigade and higher.

Detailed descriptions of the tactical radio relay systems and the associated interference assessments are

presented in Appendix D.

2.2.3 Air Combat Training Systems

The DoD has several systems that are used to train aircrews in air combat operations and maneuvering.

The Navy and the Marine Corps use the Tactical Aircrew Combat Training System (TACTS) and the

Air Force uses the Air Combat Maneuvering Instrumentation (ACMI) system, both of which are quite

similar in operation. The systems are used in such training exercises as gun scoring, no-drop bombing,

evasion and intercept tactics, and electronic warfare. These systems are deployed at fixed, large,

generally remote sites in the US and abroad.

The systems include an Airborne Instrumentation Subsystem (AIS) which is attached to a participating

aircraft. The AIS units communicate with stations of the Tracking Instrumentation Subsystem (TIS) that

are distributed throughout the associated range over which the aircraft operate. The AIS/TIS interface

allows for the recording of air operations, simulation of air combat events, precision location of

IMT-2000 Assessment

2-5

participating aircraft, simulation of land-based anti-air weapon engagements, and operations monitoring

by a master control facility. Air-ground-air and ground-to-ground communications links for these

systems all operate between 1755-1850 MHz. Theses training systems are absolutely essential in

maintaining the operational readiness of combat aircrews. Versions of these ranges are located in

California, Nevada, Utah, Arizona, Wisconsin, Alaska, Florida, North Carolina, and South Carolina.

The DoD is currently developing an additional ACTS system, the Joint Tactical Combat Training

System (JTCTS). This system has a “rangeless” capability that allows participating aircraft to engage in

training exercises anywhere other properly equipped aircraft are available. That is, it is possible to

perform air combat operations using only air-to-air links where event data is stored on the aircraft and

used later for training and debriefing once the aircraft have landed. The system can also be configured

for air-ground-air and ground-to-ground operation. This system will not necessarily replace the existing

ACTS system, but it is primarily intended to permit the training of aircrews at locations removed from

specially instrumented ranges.

Detailed descriptions of the TACTS/ACMI and JTCTS systems and the associated interference

assessments are presented in Appendix E.

2.2.4 Tactical Weapons Links

The DoD operates a number of weapons systems where communications between a launched weapon

and a controlling platform allow for the precision delivery of the weapon’s payload. The 1755-1850

MHz frequency range plays a role in the operations of several such critical systems. A classified

supplement to this report contains descriptions of these systems and associated interference assessments.

IMT-2000 Assessment

3-1

3.0 ASSESSMENT APPROACH

The goal of this effort was to assess the potential for sharing in the 1755-1850 MHz frequency band

from a technical perspective only. Assessments were two-way assessments in that analysts considered

both interference from DoD systems to IMT-2000 receivers and interference from IMT-2000 emitters to

DoD receivers. The general technical approach was to predict undesired signal power at victim

receivers by considering appropriate interfering transmitter parameters, operational configurations,

coupling between systems considering antenna orientations and propagation losses, and frequency-

dependent rejection when appropriate. Undesired received power levels and victim receiver interference

thresholds were then used to assess the potential for interference. Interference thresholds may be either

interference-to-noise ratios, desired signal-to-interference plus noise ratios, or the degradation of link

margins needed to sustain acceptable bit or symbol energy-to-noise power densities. Desired signal

levels were either calculated or provided by system users based on their experience with the design and

use of the subject system.

It was recognized that a number of the assessment parameters may not yet be finalized or may vary

depending on operational configurations. Consequently parametric assessments were performed in

many cases. Many of the appendixes contain either multiple figures showing variations in signal levels

for different values of selected parameters or tables with multiple entries for similar reasons. Parameters

that may vary include, but are not limited to, transmitter power, antenna gain, antenna pointing angles,

antenna heights, data rates, receiver selectivities, and desired signal levels.

Implementation of the general technical approach had variations depending on the particular DoD

systems being considered. For example, in the SGLS-to-IMT-2000 assessment, the primary SGLS sites

are fixed in location. In this case, a terrain-dependent propagation model could be used to establish

received signal level contours around the SGLS earth station sites for various IMT-2000 base stations

and mobile units. Multiple contours are provided in Attachment 1 to reflect variations in receive system

parameters and different SGLS transmit powers and antenna elevation angles.

In the case of mobile or transportable DoD systems, terrain-dependent propagation modeling was not

appropriate and a smooth-earth propagation model was used. Also in these cases, this initial assessment

tended to place mobile and transportable units at distance separations or altitudes that either reflected

guidance from the appropriate program office or represented communications links that would be

operating near minimally acceptable conditions. The latter approach is somewhat conservative and was

used principally to bound the limits of sharing issues. In several cases, sharing is investigated where

IMT-2000 Assessment

3-2

desired signal levels are significantly better than minimally acceptable levels. These cases are so noted

in the appendixes.

Source-to-victim configurations also varied in the assessments. In some cases one-to-one assessments

were performed where the principal source of interference was a single emitter of one system to a single

receiver of a victim system. Examples of these cases include a single AN/MRC-142 radio to a single

IMT-2000 mobile receiver (Appendix D) and a single IMT-2000 base station emitter to a single ACTS

ground receiver (Appendix E). In other cases, assessments addressed many-to-one interactions.

Examples of these cases include multiple IMT-2000 emitters to spaceborne SGLS receivers

(Appendix B) and multiple IMT-2000 emitters to DoD aircraft participating in training exercises

(Appendix E).

As reflected in the description of IMT-2000 systems, mobile wireless networks are deployed over the

period of several years. When appropriate, the assessments considered the notional build-out schedule

contained in Table A-7. Consideration of this schedule gives an approximate estimate of when certain

systems may be affected as IMT-2000 networks are built-out in the US. These estimates are not precise

and may be subject to debate but they do identify those systems particularly sensitive to large-scale

network development such as airborne and spaceborne receivers.

The technical feasibility of band segmentation is also addressed in the appendixes. In general, the

impact of implementing band segmentation plan 1 (only 1755-1805 MHz remains allocated for

government use) becomes an operational issue. For example, is there sufficient spectrum remaining to

satisfy communications requirements for multiple radio relay users or aircraft training for combat? The

answer to this depends on the numbers of units needing training and operational support. Such

determinations will be addressed in subsequent reports. For band segmentation plan 2, the size of the

area requiring accommodation by new IMT-2000 emitters is largely defined by the assessments

performed to evaluate overall sharing of the band.

The discussion above illustrates the wide variation in configurations and parameters that affect sharing

predictions. This initial assessment is best suited to establish the scope of sharing considerations and to

initiate a dialogue with parties interested in the 1755-1850 MHz frequency band. Such a dialogue can

help refine the assumptions made in the assessments, verify technical parameters, define operational

locations, configurations, and schedules, and establish common agreement on interference thresholds

and performance requirements.

IMT-2000 Assessment

4-1

4.0 CRITICAL ASSUMPTIONS

The technical assessments and the associated results are dependent on a number of critical assumptions.

These assumptions were made using engineering judgement to help initiate the consideration of sharing

issues for the 1755-1850 MHz frequency band. Revision of the assumptions as additional material on

technical parameters and operational scenarios becomes available is important to enhance the validity of

the work described in this report. The principal assumptions are listed below to aid the reader in

evaluating the assessment results. In most cases the critical assumptions are described in greater detail

in the appropriate appendix. Changes in any of the assumptions may necessitate revision of certain or

all of the assessments.

4.1 IMT-2000 ASSUMPTIONS

• The technical parameters describing IMT-2000 equipment used in this report are a reasonablerepresentation of several candidate IMT-2000 systems that may be deployed in US markets.

• Aggregate IMT-2000 electromagnetic environments for mature networks may be characterizedas described in relevant ITU-R documentation.

• IMT-2000 networks will mature over the course of several years with urban areas maturing first.

• On occasion IMT-2000 base station and mobile receivers may operate near minimally acceptableperformance levels.

4.2 SATOPS ASSUMPTIONS

• SATOPS minimum antenna elevation angles may fall between 3 and 10 degrees above thehorizon.

• SATOPS uplink transmitter powers may range from 100 watts to 10 kW.

• Existing emission spectra and frequency plan of current SATOPS uplinks are as defined in theSATOPS system description.

• SATOPS earth station antennas must support 360° azimuthal coverage.

4.3 TACTICAL RADIO RELAY ASSUMPTIONS

• Transmitter and receiver sites may occur anywhere within selected training ranges.

IMT-2000 Assessment

4-2

• National Guard and Reserve units will regularly train with radio relay systems at appropriatesites throughout the country.

• Tactical radio relay systems may occasionally operate near minimally acceptable performancelevels.

4.4 ACTS ASSUMPTIONS

• Areas around two test ranges, Cherry Point Marine Corps Air Station (MCAS) in the eastern USand Nellis Air Force Base (AFB) in the western US, may be considered typical locations fordetermining IMT-2000 aggregate environments to ACTS airborne receivers.

• For determining desired signal levels at airborne receivers, 35 km and 78 km separations fromthe ground transmitters are typical and near-maximum values, respectively, for theTACTS/ACMI. For the JTCTS, air-to-air transmitter-to-receiver separations of 78 km and 278km are typical and near-maximum values, respectively.

• An aircraft altitude of 9000 m (29,500 ft) is typical for flight training.

• ACTS ground receiver communications ranges, which affect the usable volume of space forflight training, cannot be reduced by more than ten percent due to interference from IMT-2000systems.

• ACTS ground station antenna heights of 30 m are typical or near-maximum values.

IMT-2000 Assessment

5-1

5.0 SUMMARY OF INITIAL RESULTS AND CONCLUSIONS

The appendixes to this report present the details of the interference assessments for certain DoD

equipment and possible IMT-2000 systems operating in the 1755-1850 MHz band. The results of these

initial assessments are summarized here. The results presented address only the technical aspects of

both full band sharing and the possible band segmentation plans and are based on interference analysis

conducted between systems on a one-to-one basis. Interaction among multiple systems was not

addressed during this phase. It should be noted that while many instances of undesired interactions are

predicted means to mitigate interference have been addressed to some degree. Possible interference

mitigation measures are addressed in the next section. The potential risks associated with predicted

interactions and possible implementation of mitigation measures are being assessed and will be

addressed in the next phase.

5.1 SATELLITE OPERATIONS AND IMT-2000

In full band sharing for SATOPS receivers, interference from IMT-2000 base stations is much more

severe than from the mobile stations, but both represent potentially significant interference. The higher

the orbit and the lower the elevation angle the more degradation in the link margin, given a constant

transmitter power. The negative net margins predicted for the Global Positioning System (GPS) and

geostationary orbits indicate that cochannel sharing with IMT-2000 base stations may not be feasible

even in the initial stages of IMT-2000 implementation if the predicted levels of interference are realistic.

With a fully built out IMT-2000 system, interference at the predicted levels to spacecraft in lower orbits

is predicted to be significant. Sharing with mobile stations may be less of a problem. Even so, negative

net margins are predicted at the geostationary orbit in 2003 and at the GPS orbit by 2010. Increasing

AFSCN transmitter power will minimize the interference on the uplink but will increase interference to

IMT–2000 receivers. Note that these predictions are based on traffic loading at the busy hour.

Interference levels at other times may be less, depending on the technology employed by the IMT-2000

systems, but they may not be low enough to be negligible. Analysis is ongoing to identify and address

factors which may reduce the amount of predicted interference. The operational risks associated with

the predicted levels of interference will be addressed in the next phase of this effort.

SATOPS uplink power management and antenna elevation angle restrictions may help to reduce the

affected area around the SATOPS uplink transmitter. However, if coordination regions on the order of

10 to 20 km are desired, and IMT-2000 specified interference thresholds are to be met, an order of

magnitude decrease in the undesired signal level is required. Additional measures for reducing the

IMT-2000 Assessment

5-2

uplink power at the IMT-2000 receiver coupled with the power management and antenna restrictions

must be implemented to significantly limit the affected area surrounding the uplink site.

Loss of access to 1805-1850 MHz in the near term would render some DoD satellites useless, would

preclude emergency TT&C operations with others, and may preclude launch and deployment of others.

Phased sharing may help reduce interactions between SATOPS transmitters and IMT-2000 receivers,

but coordination distances may be extremely large. Also, this approach may eventually degrade the

performance of SATOPS receivers in the bands where phased sharing is implemented.

5.2 TACTICAL RADIO RELAY AND IMT-2000

Full band sharing of the 1755-1850 MHz frequency range by the IMT-2000 and transportable tactical

radio relay may require separation distances on the order of 92 km (main-beam to main-beam) to 55 km

(side-lobe to side-lobe) based on conservative interference criteria. Satisfying such separation

requirements would be difficult at many locations with tactical radio relay operations. Even if a less

conservative interference threshold is used (sensitivity +10 dB for the IMT-2000 and –75 dBm for the

AN/GRC-226), the IMT-2000 and tactical radio relay receivers may still require 68 km and 40 km of

separation.

Loss of 1805-1850 MHz would present a significant operational risk to tactical radio relay operations as

these radios are frequency division duplex and require a minimum frequency separation between

transmit and receive frequencies of 50.125 MHz. Loss of this 45 MHz would severely hinder the ability

to support large-scale training exercises at any continental US (CONUS) location.

Implementation of phased sharing, with IMT-2000 using a listen-before-transmit capability, may

enhance the possibilities of sharing and will be evaluated during the operational assessment.

5.3 AIR COMBAT TRAINING SYSTEMS AND IMT-2000

With full band sharing, the airborne operations of ACTS systems result in large (sometimes in excess of

400 km) separation distances necessary to prevent interactions. Even in the early stages of an IMT-2000

network, interference over large distances may be possible. Required separation distances between

ground ACTS equipment and IMT-2000 systems may be well in excess of 100 km depending on site

elevations and antenna orientations.

IMT-2000 Assessment

5-3

For TACTS/ACMI systems, loss of 1805-1850 MHz would eliminate the ground-to-air frequencies,

without which the system as it is currently configured would be inoperable.

Implementation of phased sharing, with IMT-2000 using a listen-before-transmit capability, would

enhance the possibilities of sharing, although with ACTS systems the coordination area where such a

capability would be needed would be quite large.

5.4 WEAPONS CONTROL LINKS AND IMT-2000

Discussion of interactions between potential IMT-2000 systems and tactical weapons systems is

contained in the classified supplement to this report.

IMT-2000 Assessment

6-1

6.0 DISCUSSION OF MITIGATION METHODS

Individual system design considerations, environmental site planning, cooperative frequency planning,

and other cooperative measures can often mitigate the potential for harmful interference between radio

frequency systems. The implementation of interference mitigation measures can greatly enhance

opportunities for spectrum sharing. The assessments contained in Appendixes B through E and the

classified supplement include suggested means to mitigate possible harmful interference, if undesired

interactions were predicted. A complete exploration of mitigation measures was not possible given the

uncertainty of some IMT-2000 technical parameters and schedule limitations on this initial assessment.

Nevertheless, some mitigation measures have been identified and presented here in a summary form to

help initiate consideration of methods to promote spectrum sharing. The order of presentation of the

mitigation methods is not prioritized, and other parties may identify many additional methods. A

government and industry dialogue on sharing possibilities would be valuable for all concerned

organizations, as it is often the case that an interference mitigation method that is viable for one party

may be overly restrictive or untenable for the other affected party. The operational risks associated with

possible mitigation measures will be addressed in the next phase of this effort.

• In selected areas, implement an IMT-2000 network design that eliminates base station mainbeamillumination of DoD operational areas.

• In selected areas, implement an IMT-2000 network design using minimally acceptabletransmitter power levels.

• In selected areas, investigate possible IMT-2000 base station antenna nulling.

• Relocate the SATOPS uplink antennas and/or SATOPS transmission off-loading.

• Implement SATOPS antenna elevation angle restrictions.

• Reduce the out-of-beam energy of the SATOPS antennas.

• Investigate SATOPS signal blockage, use of RF absorptive material, and antenna redesign.

• Investigate SATOPS power management.

• Identify keep-out zones for IMT-2000 mobile units around designated DoD sites.

• Consider polarization discrimination between SATOPS antennas and IMT-2000 base stationantennas.

• Implement cooperative scheduling of SATOPS transmissions with IMT-2000 network operationscenters, allowing real-time frequency management.

• Investigate segmenting the 1755-1850 MHz frequency band; however, segmentation of the 1755-1850 MHz band may result in spectrum spillover into adjacent bands.

IMT-2000 Assessment

6-2

• Implement cross-polarization between IMT-2000 base stations and tactical radio relay to reducethe level of interference interactions.

• Investigate the possibility of using less conservative interference thresholds by insuring thatneither IMT-2000 systems nor DoD systems operate near minimally acceptable signal levels.

• Coordinate antenna orientation of IMT-2000 base stations with the location of the test ranges.The mainbeams of the IMT-2000 antennas should not point in the direction of training rangeground stations or of major flight activity, and the IMT-2000 base stations should not beilluminated by the mainbeams of high-gain ACTS ground station antennas.

• Coordinate training range aircraft training schedules with IMT-2000 operations, such that IMT-2000 power levels, frequencies, or antenna orientations could be adjusted to avoid mutualinterference.

• Use polarization diversity between IMT-2000 base stations and ACTS equipment, to reduceinterference levels for mainbeam-to-mainbeam interactions between IMT-2000 and ACTSequipment.

IMT-2000 Assessment

A-1

APPENDIX A – IMT-2000 SYSTEM DESCRIPTION

The greater portion of the IMT-2000 system description presented below has been provided by the

FCC. The last part of the system description presents specific technical parameters for selected

mobile wireless technologies. These technologies were selected primarily because technical data was

more available to describe these systems. The selection of these technologies for use in this

assessment does not represent an endorsement or advocacy of those systems. Some of the IMT-2000

parameters used in the assessments were calculated using communications theory and represent

notional parameters rather than the characteristics of existing hardware. The parameters contained in

this appendix were used in the assessment to help establish the scope of sharing issues. Calculated

distances, signal levels, and margins are principally intended to assist in further analyses and to help

initiate dialogue between government and industry interest groups.

IMT-2000 and 3G services are the names commonly used to refer to the next-generation mobile

wireless telecommunications services. The 3G family of services, and the systems that will provide

them, are intended to reflect a high degree of commonality and are to be compatible with each other.

These services will support mobile and fixed users employing a wide range of devices including

small pocket terminals, handheld telephones, laptop computers, and fixed-receiver equipment. 3G

services are envisioned to be ubiquitous throughout the globe, as available in a remote part of a

developing country as they are in an urban area in a highly developed country. Seamless roaming is a

key attribute. Access to services is expected to be uniform. Furthermore, the user will be able to

roam from an urban setting to a suburban one into a rural setting without loss of basic services.1

The ITU has been fostering the development of the underlying radio and network standards for what

is now defined as IMT-2000 services for over 15 years. The radio transmission technologies (RTTs)

providing for standardized 3G air-interfaces adopted in November 1998 were the culmination of

many years of arduous effort under the auspices of the ITU’s Radiocommunication Sector (ITU-R)

Task Group 8/1. These RTTs form the basis for connecting the user’s mobile or portable device to

the physical infrastructure supporting IMT-2000 services. ITU-R Task Group 8/1 also developed

methods that can be used to assess the amount of additional spectrum needed to accommodate the

expected future growth in demand for 3G mobile services.2 The ITU’s Telecommunication

Standardization (ITU-T) Sector is actively working to develop 3G signaling and communication

protocols, network requirements needed to support expected 3G services, and service definitions for

1 ITU-R Task Group 8/1 Chairman’s Report, ITU-R Radiocommunication Assembly, Istanbul, Turkey, May 2000.

2 ITU-R Recommendation M. [IMT.SPEC], ITU-R Radiocommunication Assembly, Istanbul, Turkey, May 2000.

IMT-2000 Assessment

A-2

IMT-2000 applications. Table A-1 below, derived from ITU-T Draft Recommendation Q.1701,3

describes selected essential capabilities of IMT-2000 systems.

Consumer demand for services available at any place and the expectation of high quality are key

drivers in the effort to establish commonality and compatibility of 3G terrestrial telecommunication

systems. It is estimated that by the year 2010 there will be one billion wireless subscribers

worldwide on 3G networks.4 At the present time, the worldwide penetration of wireless service is

approximately 7½ percent, and it is expected to exceed 30 percent by the end of the first decade of

the new millennium.5 There are over 1,300 cellular and second-generation terrestrial mobile service

networks currently operating worldwide, each with a limited geographic coverage. Hence, it is easy

to understand the importance of standardization in system design and service provision for 3G

services if uniform services and seamless roaming are to be provided on a regional or global scale.

Table A-1. IMT–2000 Services/Capabilities

Capabilities to support circuit and packet data at high bit rates:- 144 kb/s or higher in high mobility (vehicular) traffic- 384 kb/s or higher for pedestrian traffic- 2 Mb/s or higher for indoor trafficInteroperability and roaming among IMT–2000 family of systemsCommon billing/user profiles:- Sharing of usage/rate information between service providers- Standardized call detail recording- Standardized user profilesCapability to determine geographic position of mobiles and report it to boththe network and the mobile terminalSupport of multimedia services/capabilities:- Fixed and variable rate bit traffic- Bandwidth on demand- Asymmetric data rates in the forward and reverse links- Multimedia mail store and forward- Broadband access up to 2 Mb/s

A.1 SPECTRUM IDENTIFIED FOR IMT-2000

It is generally agreed that IMT-2000, or 3G, systems will require use of spectrum that extends beyond

that already encumbered by first- and second-generation mobile systems. A major issue in the global

debate regarding 3G system design, standards, and services that must be resolved is the amount of

common or “harmonized” spectrum that will be available on a global and regional basis to support

3G systems. For ease in roaming, to help stimulate commonality in services, and economies of scale,

3 ITU-T Draft Recommendation Q.1701, Geneva.

4 United States Talking Points for WRC 2000 on IMT–2000 spectrum requirements.

5 Id.

IMT-2000 Assessment

A-3

proponents of 3G services believe it is important to identify as much contiguous harmonized

spectrum to support worldwide 3G operations as is practical. This will stimulate the development of

global and regional coverage of 3G systems by reducing the cost and complexity for system

development, thus providing users with more cost-effective services.

Referring back to the data rates given in the first row in Table A-1, and assuming state-of-the-art data

compression capabilities, signal processing gains, and signal processor chip rates, the amount of

channel bandwidth needed to provide wireless services at 2 Mb/s could be as much as 15-20 MHz

(one-way); at 384 kb/s it could be a high as 5 MHz (one-way). Current second-generation mobile

systems easily support 9.6-14.4 kb/s data rates using channel bandwidths of 30-200 kHz, with 64 kb/s

being possible when employing sophisticated channelization and coding schemes. The 25 to over

500-fold increase in channel bandwidth needed to provide higher-end data rates dramatically

illustrates the reason for the demand for additional spectrum to support 3G wireless services.

A.2 WARC 92

At the 1992 World Administrative Radio Conference (WARC 92), 230 MHz of spectrum at 1885-

2025 MHz and 2110-2200 MHz was identified for use by countries wishing to implement 3G

systems. Shortly after WARC 92, the FCC conducted auctions for licenses in the paired 1850-

1910/1930-1990 MHz band that resulted in personnel communications service (PCS) operators being

licensed and authorized to provide advanced mobile wireless communications services throughout the

US. The success of the PCS rollout has done much to increase competition in the provision of mobile

telecommunications services in the US and at the same time has stimulated the demand for even more

advanced wireless services. Recently, countries around the world have started to license 3G systems

within paired frequency bands identified at WARC 92 - 1920-1980/2110-2170 MHz.

A.3 WRC-2000

At the WRC-2000 held in Istanbul, additional spectrum to support IMT-2000 services was

identified.6 Three frequency bands, consistent with those proposed by the US to the Conference,

were identified for use by administrations wishing to implement IMT-2000 services in addition to

those adopted at WARC 92.

6 WRC 2000 Final Acts, Istanbul, Turkey, June 2000.

IMT-2000 Assessment

A-4

A.4 IMT-2000 SYSTEM CHARACTERISTICS

During preparations for WRC 2000, the US committed to studying the feasibility of using the

1755-1850 MHz and 2500-2690 MHz bands (or parts thereof) for IMT-2000 operations. It was

understood that such a study would involve determining the impact of the operation of IMT-2000

systems on the systems already licensed to operate in these bands. The 1755-1850 MHz band is used

in the US to support Government services, mostly military space operations, air-to-air training

missions, and tactical communications operations. The 1710-1755 MHz portion of the 1700/1800

MHz band identified at WRC 2000 is currently in the process of becoming available for commercial

use and it could be made available for IMT–2000 services. The 1850-1885 MHz portion of the same

IMT-2000 band is already used to support PCS operations in the US. The 2500-2690 MHz band is

used to provide instructional television fixed services (ITFS) and multi-point distribution services

(MDS) throughout the US.

Because of the physical processes governing the propagation of radio waves in the frequency range

below 3 GHz, these frequencies can be efficiently transmitted and received by small, compact,

relatively lightweight user terminals. This feature, coupled with the ability to support high data rates,

makes them ideally suited for uses requiring mobility and portability of telecommunications services.

Any third-generation service that is targeted at a mobile clientele is most effectively provided by

taking advantage of the properties of radio waves operating below 3 GHz. Those 3G applications

where the data rates are so high that fixed terminals are needed, or terminals that require antennas so

large that they can only be employed in a stationary configuration, are better provided using

frequencies above 3 GHz that can more effectively support higher data rate systems. It is the

problem of identifying the spectrum bands that can and cannot be used to support 3G services that

forms the crux of the effort to assess the degree to which IMT-2000 services can be included in bands

already encumbered by services operating at 1755-1850 and 2500-2690 MHz.

In order to determine the impact of operating IMT-2000 systems in bands that are encumbered, it is

necessary to assess to what degree the proposed and incumbent systems can co-exist in the same

band. Stated in simplistic radio engineering terms, it is necessary to determine whether or not

harmful interference is generated into one of the systems (incumbent or proposed) by the operation of

the other(s). Furthermore, if it is determined that harmful interference is likely to occur, it is

desirable to isolate the conditions under which it occurs and whether or not there exists means to

mitigate its effects and costs associated with implementing such mitigation techniques.

IMT-2000 Assessment

A-5

The interference assessment mentioned above requires values of the technical characteristics for the

systems being studied and the ability to quantify the systems’ performance. For the case of the

incumbent systems in the bands 1755-1850 MHz and 2500-2690 MHz, it is reasonable to assume that

the pertinent parameters required for interference analysis studies are readily available to the

individuals tasked with performing the studies. In this report, technical parameters for the incumbent

DoD systems are presented in detail in the appendices that document the assessments associated with

these systems. This is not the case however for all the parameters that are required to characterize

IMT-2000 systems. These systems, many of which are in the planning or development stage, do not

have well-defined or universally accepted values associated with every system parameter. Thus it is

necessary to assume values for certain of the IMT-2000 system parameters that are to be used in the

conduct of the interference studies. When assumptions had to be made concerning values to be used

in characterizing IMT-2000 systems, an attempt was made to adopt values that are consistent with

values documented in readily available material such as the reports and recommendations of the ITU-

R, reports and findings of industry-led working groups addressing IMT-2000 issues, and absent any

other readily available information, FCC rules for second-generation (PCS) mobile systems that were

used as guides for 3G systems. In addition to values for the technical parameters themselves, it is

also necessary to assume certain characteristics of the rollout of proposed IMT-2000 services, such as

when they are likely to occur, whether there will be a time-phasing of the rollout, what regions of the

globe are likely to support rollout earlier than others, and within a region, whether there will be a

geographical preference i.e., urban versus suburban versus rural, for the rollout. These assumptions

also were based on as readily available material and information as possible.

Tables A-2 and A-3 provide information on the various IMT–2000 system parameters and rollout

characteristics that were used to help initiate the studies being addressed here.

IMT-2000 Assessment

A-6

Table A-2. Characteristics of IMT–2000 Mobile (Handset) StationsParameter/Characteristic Value Source

Transmitter Power -20dBw100 milliwatts e.i.r.p.

1 watt e.i.r.p.< 2 watts peak e.i.r.p.

US Doc 6S/16 Rev37

NTIA/FCCITU-R REC M.687-28

FCC PCS Rules 9

Antenna Gain 0 dBi - omni US Doc 6S/16 Rev3Antenna Height < 1 m Consistency with current 1st and

2nd generation mobile servicehandsets

Body Loss for handset near head 0 - 2 dB N/AAccess Techniques CDMA & TDMA ITU-R REC M.145510

Receiver Noise Figure 9 dB US Doc 6S/16 Rev3Thermal Noise Level -159 dBw/4 kHz

-135 dBw/1 MHzUS Doc 6S/16 Rev3

Operating Bandwidth CDMA20001.25 & 3.75 MHz

W-CDMA1.25 & 5.00 MHz

UWC-136 (TDMA)30 kHz (IS136)200 kHz (GSM)

ITU-R REC M.1455

Data Rates Supported 144 kb/s in1.25 MHz channel384 kb/s in 5 MHz channel

ITU-R REC M.145711

Required Carrier-to-Interference(C/I) Ratio

4 dB8dB

CITEL Executive Briefing Dec. 5,1999

Ameritech CellularPresentation12

Other Parameters Frequency stability3 dB bandwidth

out-of-band emissions (OOBE)Receiver sensitivity

ITU-R REC M.1455

N/A = Not Available

7 ITU-R Document US WG 6S/16, Rev 3, August 2000.

8 ITU-R Recommendation M.687-2, Geneva, 1997.

9 CFR, Title 47, Part 24.

10 ITU-R Recommendation M.1455, ITU-R Radiocommunication Assembly, Istanbul, Turkey, May 2000.

11 ITU-R Recommendation M.1457, ITU-R Radiocommunication Assembly, Istanbul, Turkey, May 2000.

12 CITEL Executive Briefing Dec. 5, 1999, San Diego, CA, Ameritech Cellular Presentation, Mr. Joe Cruz,

presenter.

IMT-2000 Assessment

A-7

Table A-3. Characteristics of IMT–2000 Base Stations

Parameter/Characteristic Value Source

Transmitter Power 10 W e.i.r.p.< 1640 watts, e.i.r.p.

ITU-R REC 687-2FCC PCS Rules

Antenna Gain 17 dBi per 120° sector US Doc 6S/16 Rev3

Tilt of Antenna 2.5° down US Doc 6S/16 Rev3

Antenna Pattern Reference antenna for sectoralpoint-to-multi-point applications

ITU-R REC F. 133613

ITU-R Doc 8F/714

Antenna Height 50 m40 m300 m

ITU-R 687-2US Doc 6S/16 Rev3

FCC PCS RulesAccess Techniques CDMA & TDMA ITU-R REC M.1455

Receiver Noise Figure 5 dB US Doc 6S/16 Rev3

Operating Bandwidth CDMA20001.25 & 3.75 MHz

W-CDMA1.25 & 5.00 MHz

UWC-136 (TDMA)30 kHz (IS136)200 kHz (GSM)

ITU-R REC M.1455

Data Rates Supported 144 kb/s in1.25 MHz channel384 kb/s in 5 MHz channel

ITU-R REC M.1457

Required Carrier-to-Interference(C/I) Ratio

4 dB8dB

CITEL Executive Briefing Dec. 5,1999

Ameritech CellularPresentation15

Thermal Noise Level -163dBw/4 kHz-139 dBw/1 MHz

US Doc 6S/16 Rev3

Minimum Feeder Loss 1 dB US Doc 6S/16 Rev3

Other Parameters Dynamic RangePower Control StepsFrequency Stability

3 dB bandwidthOOBE

Receiver sensitivity

ITU-R REC. M.1455

In order to perform the compatibility assessments presented in the appendices, certain specific

technical parameters needed additional definition beyond that provided in the tables above. In these

cases communications theory and reviews of second generation systems were used to help develop

the needed parameters. Tables A-4 through A-7 present the final version of the technical parameters

used in the calculations documented in the appendices. It should be noted that the assessments

13

ITU-R Recommendation F. 1336, ITU-R Radiocommunication Assembly, Istanbul, Turkey, May 2000.14

ITU-R Recommendation F. 1336, ITU-R Radiocommunication Assembly, Istanbul, Turkey, May 2000.15

See footnote 12.

IMT-2000 Assessment

A-8

considered only one CDMA system simply to limit the scope of the initial assessment. Further

analyses and discussions of sharing should consider all of the IMT-2000 technologies equally.

Table A-4. Characteristics of IMT-2000 Mobile Stations

ParameterCDMA-2000 CDMA-2000

UWC-136(TDMA)

UWC-136(TDMA)

GPRS/EDGEW-CDMA

Carrier Spacing1.25 MHz 3.75 MHz 30 kHz 200 kHz 5 MHz

Transmitter Power 100 mW 100 mW 100 mW 100 mW 100mWAntenna Gain 0 dBi 0 dBi 0 dBi 0 dBi 0 dBi

Antenna Height 1.5 m 1.5 m 1.5 m 1.5 m 1.5 m

Body Loss 0 dB 0 dB 0 dB 0 dB0 dBi

AccessTechniques

CDMA CDMA TDMA TDMA CDMA

Data RatesSupported

144 kbps 384 kbps30 kbps44 kbps 384 kbps

384 kbps

Modulation Type QPSK/BPSK QPSK/BPSK π/4-DQPSK8-PSK

GMSK8-PSK

QPSK

EmissionBandwidth

-3 dB 1.1 MHz 3.3 MHzf 0.03 MHz 0.18 MHz 3 GPP-20 dB 1.4 MHz 4.2 MHz 0.03 MHz 0.22 MHz TS25.101-60 dB 1.5 MHz 4.5 MHz 0.04 MHz 0.24 MHz

Receiver NoiseFigure

9 dB 9 dB 9 dB 9 dB 9 dB

Receiver ThermalNoise Level

-113. dBma

-105 dBmb-109 dBma

-100 dBmb -121 dBma -113 dBma -109 dBm in 384kbps

ReceiverBandwidth

-3 dB 1.10 MHz 3.30 MHz 0.03 MHz 0.18 MHz N/A-20 dB 1.6 MHz 4.7 MHz 0.04 MHz 0.25 MHz N/A-60 dB 3.7 MHz 11 MHz 0.09 MHz 0.58 MHz N/A

Eb/No for Pe = 10-3 6.6 dB 6.6 dB 7.8 dB 8.4 dB 3.1 dB*Receiver

Sensitivityc -107 dBm -103dBm -113 dBm -104 dBm -106 dBm

InterferenceThreshold 1d -119 dBm -115 dBm -127 dBm -119 dBm N/A

InterferenceThreshold 2e -104 dBm -100dBm -111dBm -103dBm N/A

ain bandwidth equal to data ratebin receiver bandwidthcFor a 10-3 raw bit error rate, theoretical Eb/NodDesired signal at sensitivity, I/N = -6 dB for a 10 percent loss in rangeeDesired signal 10 dB above sensitivity, S/(I+N) for a 10-3 BERfShaded values were estimated.* Assumes Eb/No for Pe = 10-6 without diversityN/A = Not Available

IMT-2000 Assessment

A-9

Table A-5. Characteristics of IMT-2000 Base Stations

ParameterCDMA-2000 CDMA-2000

UWC-136(TDMA)

UWC-136(TDMA)

GPRS/EDGE

W-CDMA

OperatingBandwidth

1.25 MHz 3.75 MHz 30 kHz 200 kHz 5 MHz

Transmitter Power 10 W 10 W 10 W 10 W 10 W

Antenna Gain17 dBi per 120

deg. sector17 dBi per 120

deg. sector17 dBi per 120

deg. sector17 dBi per 120

deg. sector17 dBi per 120

deg. sectorAntenna Height 40 m 40 m 40 m 40 m 40 mTilt of Antenna 2.5 degs down 2.5 degs down 2.5 degs down 2.5 degs down 2.5 degs down

AccessTechniques

CDMA CDMA TDMA TDMA CDMA

Data RatesSupported

144 kbps 384 kbps30 kbps44 kbps 384 kbps

384 kbps

Modulation Type QPSK/BPSK QPSK/BPSK π/4-DQPSK8-PSK

GMSK8-PSK

QPSK

EmissionBandwidth

-3 dB 1.1 MHz 3.3 MHzf 0.03 MHz 0.18 MHz 3 GPP-20 dB 1.4 MHz 4.2 MHz 0.03 MHz 0.22 MHz TS25.104-60 dB 1.5 MHz 4.5 MHz 0.04 MHz 0.24 MHz

Receiver NoiseFigure

5 dB 5 dB 5 dB 5 dB 5 dB

Receiver ThermalNoise Level

-117dBma

-109dBmb-113 dBma

-104 dBmb -125 dBma -117 dBma -113 dBm in384 kbps

ReceiverBandwidth

-3 dB 1.10 MHz 3.3 MHz 0.03 MHz 0.18 MHz N/A-20 dB 1.67 MHz 4.7 MHz 0.04 MHz 0.25 MHz N/A-60 dB 3.7 MHz 11 MHz 0.09 MHz 0.58 MHz N/A

Eb/No for Pe = 10-3 6.6 dB 6.6 dB 7.8 dB 8.4 dB 3.4 dB*Receiver

Sensitivityc -111 dBm -107 dBm -117 dBm -108.Bm -110 dBm

InterferenceThreshold 1d -123dBm -119dBm -131 dBm -123 dBm N/A

InterferenceThreshold 2e -108 dBm -104 dBm -115 dBm -107dBm N/A

ain bandwidth equal to data ratebin receiver bandwidthcFor a 10-3 raw bit error rate, theoretical Eb/NodDesired signal at sensitivity, I/N = -6 dB for a 10 percent loss in rangeeDesired signal 10 dB above sensitivity, S/(I+N) for a 10-3 BERfShaded values were estimated.* Assumes Eb/No for Pe = 10-6 without diversityN/A = Not Available

IMT-2000 Assessment

A-10

Table A-6. IMT-2000 Traffic Model Characteristicsa

Parameter ValueTraffic Environments Rural

VehicularPedestrian

In-building (Central business district)Maximum Data Rates Rural - 9.6 kbps

Vehicular - 144 kbpsPedestrian - 384 kbpsIn-building - 2 Mbps

Cell Size Rural - 10 km radiusVehicular - 1000 m radiusPedestrian - 315 m radiusIn-building - 40 m radius

Users per cell during busy hour Rural - not significantVehicular - 4700

Pedestrian - 42300In-building - 1275

Percent of total uplink traffic >64 kbps duringbusy hour

Rural - not significantVehicular - 34%

Pedestrian - 30%In-building - 28%

Percent of total downlink traffic >64 kbpsduring busy hour

Rural - not significantVehicular - 78%

Pedestrian - 74%In-building - 73%

Average number of users per cell per MHzduring busy hour assuming frequency duplex

operation

Rural - not significantVehicular

< 64 kbps - 16> 64 kbps - 4Pedestrian

< 64 kbps - 150> 64 kbps - 64

In-building< 64 kbps - 4> 64 kbps - 2

a Values in the table are for a mature network.

Table A-7. Rate of IMT-2000 Network Deploymenta

Calendar YearLocal

Environment2003 2006 2010

Urban 10% 50% 90%Suburban 5% 30% 60%

Rural 0% 5% 10%a For some interactions the potential for interference will be influenced by the degree to whichIMT-2000 networks are built out. Table 4 identifies assumptions that will be used in theassessments with respect to the degree to which US IMT-2000 networks are developed followingthe granting of licenses. The levels of aggregate emissions for a fully mature IMT-2000environment were taken from ITU-R 687.2 or other reference material as appropriate.

IMT 2000 Assessment

B-1

APPENDIX B – POTENTIAL INTERFERENCE TOSATELLITE OPERATIONS

This appendix provides the results of the interim assessment of interference from IMT-2000 to satellite

operations (SATOPS) uplinks.

B.1 ASSESSMENT APPROACH

The approach was derived from a previous report prepared by the Air Force Frequency Management

Agency.1 This previous report calculated the estimated interference environment into a spacecraft

receiver based upon the power density per square kilometer per Hertz generated by IMT–2000 stations

in an urban environment and the population density and urban area sizes visible from the spacecraft.

For this effort, the approach used in this report was to base the calculations of power density upon

ITU-R Report M.2023 2 rather than on the older ITU recommendation used in Reference 1. This change

allowed calculations to be performed separately for interference from Mobile Stations and Base Stations.

Since Reference 2 indicates that the expected traffic loading will be different in ITU Regions 1, 2, and 3

and will be asymmetrical in some services, it was necessary to consider these additional factors. The

aggregation of interference from multiple urban areas was taken directly from Reference 1. A typical

satellite link budget from a representative Air Force Satellite Control Network (AFSCN) transmitter to a

satellite using a common telemetry, tracking, and commanding (TT&C) transponder (the L3–Com

model CXS810–C) was used to compute the link margin in the absence of interference from IMT-2000

transmitters. The aggregate interference level from the IMT-2000 environment was then used to

compute the net margin.

B.2 LINK MARGIN CALCULATIONS

Four satellite orbits were chosen for the assessment:

• A 250-kilometer orbit, typical of the Space Transportation System (STS)

• An 833-kilometer orbit, typical of meteorological satellites such as Defense MeteorologicalSatellite Program (DMSP)

1 Wayne Wamback, The Potential for Interference Between IMT-2000 Systems and U.S. DoD Systems Operating in the

Frequency Band 1755 – 1850 MHz, Washington, DC: Air Force Frequency Management Agency, 28 February 2000.2 Spectrum Requirements for International Mobile Telecommunications–2000 (IMT–2000), Report ITU–R M.2023,

Geneva, Switzerland, 2000.

IMT 2000 Assessment

B-2

• A 22,200-kilometer orbit, typical of the Global Positioning System (GPS)

• A 35,784-kilometer orbit, typical of geostationary satellites

For the two lowest orbits, three hypothetical AFSCN transmitter powers, 250 W, 2000 W, and 7000 W,

were used in the assessment. For the other two orbits only the 2000 W and 7000 W powers were used.

These power levels may not be the actual powers normally used in AFSCN operations, but are

representative of AFSCN capabilities.

Antenna characteristics were taken from an AFSCN Specification.3 For this assessment, a 46-foot

antenna with a gain of 41 dBi was selected for the AFSCN station. A spacecraft antenna with a –5 dBi

gain was assumed as typical. Propagation losses took into account free-space path loss, cloud loss, rain

loss, atmospheric loss, and polarization loss based on the slant-range to the spacecraft. Three AFSCN

station elevation angles were used to determine the losses through the earth’s atmosphere.

The spacecraft effective receiver system temperature was 798 Kelvin, and the threshold service powers

were –113 dBm for the Command service and –120 dBm for the Carrier and Ranging services.

Link margin calculations were based on the traffic loading characteristics of ITU Region 2 (the

Americas). The aggregation of interference taken from Reference 1 did not distinguish between ITU

regions. Since the power densities per square kilometer per Hertz from the other regions differed by less

than 1 dB for the Base Stations and by approximately 3 dB for the Mobile Stations, it is reasonable to

assume that the Region 2 values are indicative of the interference environment worldwide.

An example of the link budget and the net margin calculations is shown in Table B-1. The results of the

link margin calculations are shown in Tables B-2 through B-9. Separate tables are shown for

interference from mobile stations and base stations for each of the years 2003, 2006, and 2010 as well as

for a future full buildout of the IMT-2000 system.

It was assumed that the worst-case IMT–2000 power density that a spacecraft receiver is exposed to is

independent of orbital altitude. The implication is that the increase in received power due to the

increase in quantities of IMT-2000 transmitters visible to the spacecraft as the altitude increases is offset

by the propagation path loss increase with altitude. The limited data included in Reference 1 suggest

that the error associated with this assumption may be less than 4 dB. Verification of this assumption

3 Standardized Interface Specification between Air Force Satellite Control Network Common User Element and

Comm/Range Segment and Space Vehicle, AFSCN SIS-000502A, El Segundo, CA, Space and Missiles System Center, 22October 1997.

IMT 2000 Assessment

B-3

would have required a more detailed simulation than was possible in the time available for this interim

analysis.

B.3 CONCLUSIONS

Interference from IMT–2000 base stations is much more severe than from the mobile stations, but both

represent potentially significant interference to SATOPS. The higher the orbit and the lower the

elevation angle the more degradation in the link margin, given a constant transmitter power. The

negative net margins predicted for the Global Positioning System (GPS) and geostationary orbits

indicate that cochannel sharing with IMT-2000 base stations may not be feasible even in the initial

stages of IMT-2000 implementation if the predicted levels of interference are realistic. With a fully built

out IMT-2000 system, interference at the predicted levels to spacecraft in lower orbits is expected to be

significant. Sharing with mobile stations will be less of a problem. Even so, negative net margins are

predicted at the geostationary orbit in 2003 and at the GPS orbit by 2010. Increasing AFSCN

transmitter power will minimize the interference on the uplink, but will increase interference to IMT-

2000 receivers. Note that these predictions are based on traffic loading at the busy hour. Interference

levels at other times may be less, depending on the technology employed by the IMT–2000 systems, but

may not be low enough to be negligible.

This interim assessment represents a worst-case situation. There are several factors, not considered in

this assessment due to time constraints, which may reduce the amount of interference predicted. These

factors include the vertical radiation patterns of the IMT–2000 base station antennas, power

management in the IMT–2000 systems, variations among IMT–2000 technologies, and the

approximations inherent in the algorithms used to predict the aggregate interference. Further analysis is

ongoing and the results will be incorporated in the final assessment.

The operational impact of the predicted levels of interference needs to be addressed. Implementation

strategies also need to be investigated to determine if it is feasible to implement the IMT-2000 buildout

in a way which could mitigate interference to SATOPS.

IMT 2000 Assessment

B-4

Table B-1. Typical Link BudgetTypical Link Budget

Frequency 1800.0 MHzTX Power 7000.0 WattsTX Power 68.5 dBmTX EIRP 107.0 dBmTX Ant Diameter 46.0 Ft From SIS-0502TX Ant Beamwidth 0.6 DegTX Ant Gain 41.0 dBi From SIS-0502Orbit Height 20200.0 KmElevation Angle 10.0 DegMean Earth Radius 6378.1 KmSlant Range 24717.7 KmSpace Loss 185.4 dBCloud Loss 0.0 dBRain Loss 1.6 dBAtmospheric Loss 0.2 dBPolarization Loss 0.5 dBScintillation Loss 0.0 dBRx Antenna Gain -5.0 dBRx Antenna Temp 300.0 KRx Diplexer Loss 0.3 dBRx Coupler Loss 1.0 dBRx Cable Loss 2.0 dBRx Cable Temp 169.6 KTotal Rx Line Loss 3.3 dBReceiver NF 5.0 dBReceiver Temp 627.1 KEff Rx Ant Temp 171.0 KRx System Temp 798.1 KRx System Temp 29.0 KRx System Gain -5.0 dBRx G/T -34.0 dB/KRx Isotropic Carrier Pwr -86.5 dBm

CMD Carrier RangingMod Index 0.6 0.3Mod Loss -7.8 -0.6 -10.8 dBMin Received Service Power -94.3 -87.1 -97.3 dBmThreshold Service Power for aCXS810-C

-113.0 -120.0 -120.0 dBm From L3-Com Spec

Data Rate 2048.0 Kb/s From SIS-0502Link Margin 18.7 32.9 22.7 dBSystem Noise -198.3 -198.3 -198.3 dBW/HzIMT-2000 Noise -161.4 -161.4 -161.4 dBW/HzNet Margin -18.2 -4.0 -14.2 dB

IMT 2000 Assessment

B-5

Table B-2. Interference from IMT-2000 Mobile Stations in 2003Link Margin Net Margin

Typical Orbit AFSCN Elevation Without Interference (dB) With Interference (dB)Spacecraft Altitude TX Power Angle Command Carrier Ranging Command Carrier Ranging

STS 250 km 250 W 3 deg 28.2 42.4 32.2 18.2 32.4 22.25 deg 29.4 43.6 33.4 19.4 33.6 23.4

10 deg 32.0 46.2 36.0 22.0 36.2 26.02000 W 3 deg 37.2 51.4 41.2 27.2 41.4 31.2

5 deg 38.4 52.6 42.4 28.4 42.6 32.510 deg 41.0 55.2 45.0 31.0 45.2 35.0

7000 W 3 deg 42.6 56.8 46.7 32.6 46.8 36.75 deg 43.9 58.1 47.9 33.9 48.1 37.9

10 deg 46.5 60.7 50.5 36.5 50.7 40.5

DMSP 833 km 250 W 3 deg 22.0 36.2 26.0 12.0 26.2 16.05 deg 22.8 37.0 26.8 12.8 27.0 16.8

10 deg 24.3 38.5 28.4 14.3 28.5 18.42000 W 3 deg 31.0 45.2 35.1 21.0 35.2 25.1

5 deg 31.8 46.0 35.8 21.8 36.0 25.810 deg 33.4 47.6 37.4 23.4 37.6 27.4

7000 W 3 deg 36.5 50.7 40.5 26.5 40.7 30.55 deg 37.2 51.4 41.3 27.2 41.4 31.3

10 deg 38.8 53.0 42.8 28.8 43.0 32.8

GPS 20,200 km 2000 W 3 deg 12.6 26.8 16.6 2.6 16.8 6.65 deg 12.9 27.1 16.9 2.9 17.1 6.9

10 deg 13.2 27.4 17.3 3.2 17.4 7.37000 W 3 deg 18.0 32.2 22.1 8.0 22.2 12.1

5 deg 18.3 32.5 22.3 8.3 22.5 12.310 deg 18.7 32.9 22.7 8.7 22.9 12.7

GEO 35,784 km 2000 W 3 deg 8.4 22.6 12.4 -1.6 12.6 2.45 deg 8.6 22.8 12.7 -1.4 12.8 2.7

10 deg 8.9 23.1 12.9 -1.1 13.1 2.97000 W 3 deg 13.8 28.0 17.8 3.8 18.0 7.8

5 deg 14.1 28.3 18.1 4.1 18.3 8.110 deg 14.4 28.6 18.4 4.4 18.6 8.4

IMT 2000 Assessment

B-6

Table B-3. Interference from IMT-2000 Mobile Stations in 2006Link Margin Net Margin

Typical Orbit AFSCN Elevation Without Interference (dB) With Interference (dB)Spacecraft Altitude TX Power Angle Command Carrier Ranging Command Carrier Ranging

STS 250 km 250 W 3 deg 28.2 42.4 32.2 11.2 25.4 15.25 deg 29.4 43.6 33.4 12.4 26.6 16.4

10 deg 32.0 46.2 36.0 15.0 29.2 19.02000 W 3 deg 37.2 51.4 41.2 20.2 34.4 24.2

5 deg 38.4 52.6 42.4 21.4 35.6 25.510 deg 41.0 55.2 45.0 24.0 38.2 28.1

7000 W 3 deg 42.6 56.8 46.7 25.7 39.9 29.75 deg 43.9 58.1 47.9 26.9 41.1 30.9

10 deg 46.5 60.7 50.5 29.5 43.7 33.5

DMSP 833 km 250 W 3 deg 22.0 36.2 26.0 5.0 19.2 9.05 deg 22.8 37.0 26.8 5.8 20.0 9.8

10 deg 24.3 38.5 28.4 7.3 21.5 11.42000 W 3 deg 31.0 45.2 35.1 14.0 28.2 18.1

5 deg 31.8 46.0 35.8 14.8 29.0 18.810 deg 33.4 47.6 37.4 16.4 30.6 20.4

7000 W 3 deg 36.5 50.7 40.5 19.5 33.7 23.55 deg 37.2 51.4 41.3 20.3 34.5 24.3

10 deg 38.8 53.0 42.8 21.8 36.0 25.8

GPS 20,200 km 2000 W 3 deg 12.6 26.8 16.6 -4.4 9.8 -0.45 deg 12.9 27.1 16.9 -4.1 10.1 -0.1

10 deg 13.2 27.4 17.3 -3.8 10.4 0.37000 W 3 deg 18.0 32.2 22.1 1.0 15.2 5.1

5 deg 18.3 32.5 22.3 1.3 15.5 5.310 deg 18.7 32.9 22.7 1.7 15.9 5.7

GEO 35,784 km 2000 W 3 deg 8.4 22.6 12.4 -8.6 5.6 -4.65 deg 8.6 22.8 12.7 -8.4 5.8 -4.3

10 deg 8.9 23.1 12.9 -8.1 6.1 -4.07000 W 3 deg 13.8 28.0 17.8 -3.2 11.0 0.9

5 deg 14.1 28.3 18.1 -2.9 11.3 1.110 deg 14.4 28.6 18.4 -2.6 11.6 1.4

IMT 2000 Assessment

B-7

Table B-4. Interference from IMT-2000 Mobile Stations in 2010Link Margin Net Margin

Typical Orbit AFSCN Elevation Without Interference (dB) With Interference (dB)Spacecraft Altitude TX Power Angle Command Carrier Ranging Command Carrier Ranging

STS 250 km 250 W 3 deg 28.2 42.4 32.2 8.7 22.9 12.75 deg 29.4 43.6 33.4 9.9 24.1 13.9

10 deg 32.0 46.2 36.0 12.5 26.7 16.52000 W 3 deg 37.2 51.4 41.2 17.7 31.9 21.7

5 deg 38.4 52.6 42.4 18.9 33.1 23.010 deg 41.0 55.2 45.0 21.5 35.7 25.6

7000 W 3 deg 42.6 56.8 46.7 23.2 37.4 27.25 deg 43.9 58.1 47.9 24.4 38.6 28.4

10 deg 46.5 60.7 50.5 27.0 41.2 31.0

DMSP 833 km 250 W 3 deg 22.0 36.2 26.0 2.5 16.7 6.55 deg 22.8 37.0 26.8 3.2 17.4 7.3

10 deg 24.3 38.5 28.4 4.8 19.0 8.82000 W 3 deg 31.0 45.2 35.1 11.5 25.7 15.6

5 deg 31.8 46.0 35.8 12.3 26.5 16.310 deg 33.4 47.6 37.4 13.9 28.1 17.9

7000 W 3 deg 36.5 50.7 40.5 17.0 31.2 21.05 deg 37.2 51.4 41.3 17.8 32.0 21.8

10 deg 38.8 53.0 42.8 19.3 33.5 23.3

GPS 20,200 km 2000 W 3 deg 12.6 26.8 16.6 -6.9 7.3 -2.95 deg 12.9 27.1 16.9 -6.6 7.6 -2.6

10 deg 13.2 27.4 17.3 -6.3 7.9 -2.27000 W 3 deg 18.0 32.2 22.1 -1.5 12.7 2.6

5 deg 18.3 32.5 22.3 -1.2 13.0 2.810 deg 18.7 32.9 22.7 -0.8 13.4 3.2

GEO 35,784 km 2000 W 3 deg 8.4 22.6 12.4 -11.2 3.0 -7.15 deg 8.6 22.8 12.7 -10.9 3.3 -6.9

10 deg 8.9 23.1 12.9 -10.6 3.6 -6.67000 W 3 deg 13.8 28.0 17.8 -5.7 8.5 -1.7

5 deg 14.1 28.3 18.1 -5.5 8.7 -1.410 deg 14.4 28.6 18.4 -5.2 9.0 -1.2

IMT 2000 Assessment

B-8

Table B-5. Interference from IMT-2000 Mobile Stations at Full BuildoutLink Margin Net Margin

Typical Orbit AFSCN Elevation Without Interference (dB) With Interference (dB)Spacecraft Altitude TX Power Angle Command Carrier Ranging Command Carrier Ranging

STS 250 km 250 W 3 deg 28.2 42.4 32.2 8.2 22.4 12.25 deg 29.4 43.6 33.4 9.4 23.6 13.5

10 deg 32.0 46.2 36.0 12.0 26.2 16.12000 W 3 deg 37.2 51.4 41.2 17.2 31.4 21.3

5 deg 38.4 52.6 42.4 18.5 32.7 22.510 deg 41.0 55.2 45.0 21.1 35.3 25.1

7000 W 3 deg 42.6 56.8 46.7 22.7 36.9 26.75 deg 43.9 58.1 47.9 23.9 38.1 27.9

10 deg 46.5 60.7 50.5 26.5 40.7 30.5

DMSP 833 km 250 W 3 deg 22.0 36.2 26.0 2.0 16.2 6.05 deg 22.8 37.0 26.8 2.8 17.0 6.8

10 deg 24.3 38.5 28.4 4.3 18.5 8.42000 W 3 deg 31.0 45.2 35.1 11.1 25.3 15.1

5 deg 31.8 46.0 35.8 11.8 26.0 15.910 deg 33.4 47.6 37.4 13.4 27.6 17.4

7000 W 3 deg 36.5 50.7 40.5 16.5 30.7 20.55 deg 37.2 51.4 41.3 17.3 31.5 21.3

10 deg 38.8 53.0 42.8 18.8 33.0 22.9

GPS 20,200 km 2000 W 3 deg 12.6 26.8 16.6 -7.4 6.8 -3.35 deg 12.9 27.1 16.9 -7.1 7.1 -3.1

10 deg 13.2 27.4 17.3 -6.7 7.5 -2.77000 W 3 deg 18.0 32.2 22.1 -1.9 12.3 2.1

5 deg 18.3 32.5 22.3 -1.6 12.6 2.410 deg 18.7 32.9 22.7 -1.3 12.9 2.7

GEO 35,784 km 2000 W 3 deg 8.4 22.6 12.4 -11.6 2.6 -7.65 deg 8.6 22.8 12.7 -11.4 2.8 -7.3

10 deg 8.9 23.1 12.9 -11.1 3.1 -7.17000 W 3 deg 13.8 28.0 17.8 -6.2 8.0 -2.2

5 deg 14.1 28.3 18.1 -5.9 8.3 -1.910 deg 14.4 28.6 18.4 -5.6 8.6 -1.6

IMT 2000 Assessment

B-9

Table B-6. Interference from IMT-2000 Base Stations in 2003Link Margin Net Margin

Typical Orbit AFSCN Elevation Without Interference (dB) With Interference (dB)Spacecraft Altitude TX Power Angle Command Carrier Ranging Command Carrier Ranging

STS 250 km 250 W 3 deg 28.2 42.4 32.2 1.3 15.5 5.35 deg 29.4 43.6 33.4 2.5 16.7 6.6

10 deg 32.0 46.2 36.0 5.1 19.3 9.22000 W 3 deg 37.2 51.4 41.2 10.3 24.5 14.4

5 deg 38.4 52.6 42.4 11.6 25.8 15.610 deg 41.0 55.2 45.0 14.2 28.4 18.2

7000 W 3 deg 42.6 56.8 46.7 15.8 30.0 19.85 deg 43.9 58.1 47.9 17.0 31.2 21.0

10 deg 46.5 60.7 50.5 19.6 33.8 23.6

DMSP 833 km 250 W 3 deg 22.0 36.2 26.0 -4.9 9.3 -0.85 deg 22.8 37.0 26.8 -4.1 10.1 -0.1

10 deg 24.3 38.5 28.4 -2.5 11.7 1.52000 W 3 deg 31.0 45.2 35.1 4.2 18.4 8.2

5 deg 31.8 46.0 35.8 4.9 19.1 9.010 deg 33.4 47.6 37.4 6.5 20.7 10.5

7000 W 3 deg 36.5 50.7 40.5 9.6 23.8 13.65 deg 37.2 51.4 41.3 10.4 24.6 14.4

10 deg 38.8 53.0 42.8 11.9 26.1 16.0

GPS 20,200 km 2000 W 3 deg 12.6 26.8 16.6 -14.3 -0.1 -10.25 deg 12.9 27.1 16.9 -14.0 0.2 -10.0

10 deg 13.2 27.4 17.3 -13.6 0.6 -9.67000 W 3 deg 18.0 32.2 22.1 -8.8 5.4 -4.8

5 deg 18.3 32.5 22.3 -8.5 5.7 -4.510 deg 18.7 32.9 22.7 -8.2 6.0 -4.2

GEO 35,784 km 2000 W 3 deg 8.4 22.6 12.4 -18.5 -4.3 -14.55 deg 8.6 22.8 12.7 -18.2 -4.0 -14.2

10 deg 8.9 23.1 12.9 -17.9 -3.7 -13.97000 W 3 deg 13.8 28.0 17.8 -13.0 1.2 -9.0

5 deg 14.1 28.3 18.1 -12.8 1.4 -8.810 deg 14.4 28.6 18.4 -12.5 1.7 -8.5

IMT 2000 Assessment

B-10

Table B-7. Interference from IMT-2000 Base Stations in 2006Link Margin Net Margin

Typical Orbit AFSCN Elevation Without Interference (dB) With Interference (dB)Spacecraft Altitude TX Power Angle Command Carrier Ranging Command Carrier Ranging

STS 250 km 250 W 3 deg 28.2 42.4 32.2 -5.7 8.5 -1.75 deg 29.4 43.6 33.4 -4.4 9.8 -0.4

10 deg 32.0 46.2 36.0 -1.9 12.3 2.22000 W 3 deg 37.2 51.4 41.2 3.4 17.6 7.4

5 deg 38.4 52.6 42.4 4.6 18.8 8.610 deg 41.0 55.2 45.0 7.2 21.4 11.2

7000 W 3 deg 42.6 56.8 46.7 8.8 23.0 12.85 deg 43.9 58.1 47.9 10.0 24.2 14.0

10 deg 46.5 60.7 50.5 12.6 26.8 16.6

DMSP 833 km 250 W 3 deg 22.0 36.2 26.0 -11.8 2.4 -7.85 deg 22.8 37.0 26.8 -11.1 3.1 -7.1

10 deg 24.3 38.5 28.4 -9.5 4.7 -5.52000 W 3 deg 31.0 45.2 35.1 -2.8 11.4 1.2

5 deg 31.8 46.0 35.8 -2.0 12.2 2.010 deg 33.4 47.6 37.4 -0.5 13.7 3.5

7000 W 3 deg 36.5 50.7 40.5 2.6 16.8 6.65 deg 37.2 51.4 41.3 3.4 17.6 7.4

10 deg 38.8 53.0 42.8 5.0 19.2 9.0

GPS 20,200 km 2000 W 3 deg 12.6 26.8 16.6 -21.3 -7.1 -17.25 deg 12.9 27.1 16.9 -21.0 -6.8 -17.0

10 deg 13.2 27.4 17.3 -20.6 -6.4 -16.67000 W 3 deg 18.0 32.2 22.1 -15.8 -1.6 -11.8

5 deg 18.3 32.5 22.3 -15.5 -1.3 -11.510 deg 18.7 32.9 22.7 -15.2 -1.0 -11.2

GEO 35,784 km 2000 W 3 deg 8.4 22.6 12.4 -25.5 -11.3 -21.45 deg 8.6 22.8 12.7 -25.2 -11.0 -21.2

10 deg 8.9 23.1 12.9 -24.9 -10.7 -20.97000 W 3 deg 13.8 28.0 17.8 -20.0 -5.8 -16.0

5 deg 14.1 28.3 18.1 -19.8 -5.6 -15.810 deg 14.4 28.6 18.4 -19.5 -5.3 -15.5

IMT 2000 Assessment

B-11

Table B-8. Interference from IMT-2000 Base Stations in 2010Link Margin Net Margin

Typical Orbit AFSCN Elevation Without Interference (dB) With Interference (dB)Spacecraft Altitude TX Power Angle Command Carrier Ranging Command Carrier Ranging

STS 250 km 250 W 3 deg 28.2 42.4 32.2 -8.2 6.0 -4.25 deg 29.4 43.6 33.4 -7.0 7.2 -3.0

10 deg 32.0 46.2 36.0 -4.4 9.8 -0.42000 W 3 deg 37.2 51.4 41.2 0.8 15.0 4.8

5 deg 38.4 52.6 42.4 2.0 16.2 6.110 deg 41.0 55.2 45.0 4.6 18.8 8.6

7000 W 3 deg 42.6 56.8 46.7 6.2 20.4 10.35 deg 43.9 58.1 47.9 7.5 21.7 11.5

10 deg 46.5 60.7 50.5 10.1 24.3 14.1

DMSP 833 km 250 W 3 deg 22.0 36.2 26.0 -14.4 -0.2 -10.45 deg 22.8 37.0 26.8 -13.6 0.6 -9.6

10 deg 24.3 38.5 28.4 -12.1 2.1 -8.02000 W 3 deg 31.0 45.2 35.1 -5.4 8.8 -1.3

5 deg 31.8 46.0 35.8 -4.6 9.6 -0.610 deg 33.4 47.6 37.4 -3.0 11.2 1.0

7000 W 3 deg 36.5 50.7 40.5 0.1 14.3 4.15 deg 37.2 51.4 41.3 0.8 15.0 4.9

10 deg 38.8 53.0 42.8 2.4 16.6 6.4

GPS 20,200 km 2000 W 3 deg 12.6 26.8 16.6 -23.8 -9.6 -19.85 deg 12.9 27.1 16.9 -23.5 -9.3 -19.5

10 deg 13.2 27.4 17.3 -23.2 -9.0 -19.17000 W 3 deg 18.0 32.2 22.1 -18.4 -4.2 -14.3

5 deg 18.3 32.5 22.3 -18.1 -3.9 -14.110 deg 18.7 32.9 22.7 -17.7 -3.5 -13.7

GEO 35,784 km 2000 W 3 deg 8.4 22.6 12.4 -28.0 -13.8 -24.05 deg 8.6 22.8 12.7 -27.8 -13.6 -23.7

10 deg 8.9 23.1 12.9 -27.5 -13.3 -23.57000 W 3 deg 13.8 28.0 17.8 -22.6 -8.4 -18.6

5 deg 14.1 28.3 18.1 -22.3 -8.1 -18.310 deg 14.4 28.6 18.4 -22.0 -7.8 -18.0

IMT 2000 Assessment

B-12

Table B-9. Interference from IMT-2000 Base Stations at Full BuildoutLink Margin Net Margin

Typical Orbit AFSCN Elevation Without Interference (dB) With Interference (dB)Spacecraft Altitude TX Power Angle Command Carrier Ranging Command Carrier Ranging

STS 250 km 250 W 3 deg 28.2 42.4 32.2 -8.7 5.5 -4.75 deg 29.4 43.6 33.4 -7.5 6.7 -3.4

10 deg 32.0 46.2 36.0 -4.9 9.3 -0.82000 W 3 deg 37.2 51.4 41.2 0.3 14.5 4.4

5 deg 38.4 52.6 42.4 1.6 15.8 5.610 deg 41.0 55.2 45.0 4.2 18.4 8.2

7000 W 3 deg 42.6 56.8 46.7 5.8 20.0 9.85 deg 43.9 58.1 47.9 7.0 21.2 11.0

10 deg 46.5 60.7 50.5 9.6 23.8 13.6

DMSP 833 km 250 W 3 deg 22.0 36.2 26.0 -14.9 -0.7 -10.85 deg 22.8 37.0 26.8 -14.1 0.1 -10.1

10 deg 24.3 38.5 28.4 -12.5 1.7 -8.52000 W 3 deg 31.0 45.2 35.1 -5.8 8.4 -1.8

5 deg 31.8 46.0 35.8 -5.1 9.1 -1.010 deg 33.4 47.6 37.4 -3.5 10.7 0.5

7000 W 3 deg 36.5 50.7 40.5 -0.4 13.8 3.65 deg 37.2 51.4 41.3 0.4 14.6 4.4

10 deg 38.8 53.0 42.8 1.9 16.1 6.0

GPS 20,200 km 2000 W 3 deg 12.6 26.8 16.6 -24.3 -10.1 -20.25 deg 12.9 27.1 16.9 -24.0 -9.8 -20.0

10 deg 13.2 27.4 17.3 -23.6 -9.4 -19.67000 W 3 deg 18.0 32.2 22.1 -18.8 -4.6 -14.8

5 deg 18.3 32.5 22.3 -18.5 -4.3 -14.510 deg 18.7 32.9 22.7 -18.2 -4.0 -14.2

GEO 35,784 km 2000 W 3 deg 8.4 22.6 12.4 -28.5 -14.3 -24.55 deg 8.6 22.8 12.7 -28.2 -14.0 -24.2

10 deg 8.9 23.1 12.9 -27.9 -13.7 -23.97000 W 3 deg 13.8 28.0 17.8 -23.0 -8.8 -19.0

5 deg 14.1 28.3 18.1 -22.8 -8.6 -18.810 deg 14.4 28.6 18.4 -22.5 -8.3 -18.5

IMT 2000 Assessment

C-1

APPENDIX C – POTENTIAL INTERFERENCE FROMSATELLITE OPERATIONS UPLINK TO IMT-2000RECEIVERS

The US Department of Defense conducts satellite operations (SATOPS) functions in the1755-1850 MHz and 2200-2290 MHz bands to maintain control and receive health and status data onover 120 satellites flying in both geostationary and non-geostationary orbits. The consideration ofIMT-2000 operations within S-band raises the potential for interference both to and from SATOPS.This appendix addresses the potential for interference from the SATOPS uplink to IMT-2000receivers.

C.1 ASSESSMENT APPROACH

In order to assess the potential for interference to a geographically dispersed network of IMT-2000fixed and mobile receivers, an automated model was used to generate received signal overlays as afunction of transmitter and receiver parameters and terrain-dependent path loss. The results aredisplayed as a raster or grid of color-coded signal levels overlayed on a map. The basis for the terrain-dependent path loss calculations within the model is the Terrain-Dependent Path Loss Model(TIREM).

In recognition of the significant variations in SATOPS transmitter uplink and IMT-2000 receiverconfigurations, a parametric analysis was performed. For SATOPS uplink functions, minimumantenna elevation angles of 3, 5, and 10 degrees were selected. Additional higher minimum elevationangles were not considered because the minimal benefit in sidelobe reduction was offset by thesignificant impact to operations. Based on current antenna configurations, significant sidelobereduction is not realized until well outside of the mainbeam. These angles would be prohibitively largefor typical SATOPs functions, particularly for those conducted on satellites flying in non-geostationaryorbits.

For the IMT-2000 receivers, separate overlays were generated for the base stations andmobiles/portables in recognition of the differences in receiver antenna height, antenna gain, andinterference threshold.

IMT 2000 Assessment

C-2

C.2 SATOPS SYSTEMS DESCRIPTION

The DoD SATOPS uplink functions, which include the transmission of commanding and rangingsignals, are performed in the 1755-1850 MHz band. Downlink telemetry data is passed via the2200-2290 MHz band. The Air Force Satellite Control Network (AFSCN) is a worldwide network ofUS Air Force ground stations and control centers which provide telemetry, tracking, and commanding(TT&C) services to DoD satellites. The AFSCN consists of two control nodes, Schriever AFB, CO,and Onizuka Air station (OAS) at Sunnyvale, CA, plus eight Automated Remote Tracking Stations(ARTS) dispersed both within and outside the US. Figure C-1 depicts the locations of the AFSCNground stations. Table C-1 lists the terminal sizes and locations for the US sites considered in thisassessment. The Navy also operates Space Ground Link Subsystem (SGLS) earth stations at thefollowing locations: Prospect Harbor, ME, Laguna Peak, CA, Finegayan, Guam, as well as BlossomPoint, MD, and Quantico, VA.

Figure C-1. Locations of the AFSCN Ground Stations

IMT 2000 Assessment

C-3

Table C-1. SATOPS Uplink Sites Included in this Assessment

Terminal Name Abbreviation Alt Name LocationLatitude/

LongitudeNumber ofTerminals

Terminal Size(feet)

Colorado Tracking Station CTS Pike Colorado Springs, CO 38 48 21 N104 31 43 W 1 33

New HampshireTracking Station NHS Boss Manchester, NH 42 56 52 N

071 37 37 W 3604633

Onizuka Air Station OAS Sun Sunnyvale, CA 37 24 25 N122 0134 W 1 51

Eastern Vehicle Check-outFacility EVCF EVCF Cape Canaveral, FL 28 27 29 N

080 34 32 W 1 23

Table C-2 lists the 20 center frequencies for the standard AFSCN uplink frequency plan. It should benoted that historically, most SATOPS uplinks conformed to the 20-channel plan. However, in aneffort to become more spectrally efficient, plans are in effect to deploy hardware with the capability totune to channels in-between those reflected in the standard plan.

Figure C-2 is a computer generated emission signature of the SATOPS uplink spectrum showing thecombined baseband command, data, and ranging signal as a function of the high-power amplifier(HPA) and filtering. The figure clearly shows the benefit of baseband filtering, a technique that iscurrently not implemented at the AFSCN sites. In the absence of such filtering, the undesirable spectralproducts and limited roll-off of the out-of-band components is apparent. As will be discussed, thewideband unfiltered structure of the current SGLS waveform transmitted using the current class Camplifiers limits the benefits obtained from off-tuning SATOPS and IMT-2000 systems.

Table C-2. AFSCN SATOPS Uplink Frequency Plan

S-bandChannel

Uplink Frequency Transmission(MHz)

S-bandChannel

Uplink Frequency Transmission(MHz)

1 1763.720703 11 1803.7597662 1767.724609 12 1807.7636723 1771.728515 13 1811.7675784 1775.732422 14 1815.7714845 1779.736328 15 1819.7753916 1783.740234 16 1823.7792977 1787.744141 17 1827.7832038 1791.748047 18 1831.7871099 1795.751953 19 1835.79101610 1799.755859 20 1839.794922

C.3 MODEL INPUTS

Table C-3 lists the IMT-2000 data used to generate the received signal overlays. This data has beencoordinated with the FCC and is consistent with IMT-2000 system specifications used to assess the

IMT 2000 Assessment

C-4

other types of DoD systems in the band. Receiver interference thresholds are grouped into 10-dB binsfrom the most sensitive threshold provided (-121 dBm) up to greater than -71 dBm. This range ofthresholds more than encompasses the region of acceptable interference values.

Figure C-2. A Computer Generated Emission Signature of the SATOPS Uplink

Table C-3. IMT-2000 Receiver Data

IMT-2000Platform

Receiver InterferenceThresholds Plotted (dBm)

Receiver AntennaHeight (Meters)

Receiver AntennaGain (dBi)

Fixed BaseStations

<-121-111 to -121-101 to -111-91 to -101-81 to -91-71 to -81

> -71

40 17

Mobiles andPortables

<-105-95 to -105-85 to -95-75 to -85

>-75

1.5 0

Table C-4 lists the SATOPS uplink parameters used in the assessment. Transmitter maximum powersin the table represent the maximum transmitter capability of the high power amplifier connected to theterminal. A minimum power of 100 watts was selected under the assumption that link closure withsufficient margin can be achieved at this level. It is recognized that in some instances a minimumtransmit power of 250 watts, 500 watts, or even 1 kW is desired for adequate link margin. However,

PSD at in/output HPAWith Baseband Filter

PSD at in/output HPAWithout Baseband Filter Combined Baseband Command,

Data and Ranging Signal Without Baseband Filter

Combined Baseband Command, Data,and Ranging Signal With Baseband Filter

35 dB

IMT 2000 Assessment

C-5

results from the overlays will indicate that several dB of variation in the transmit power assumptionswill not change the conclusions that can be drawn from the data. Antenna off-axis gains weredetermined from antenna patterns provided by the Aerospace Corporation. Antenna off-axis gain atthe horizon was calculated assuming 3, 5, and 10-degree minimum elevation angles. As discussed inthe approach, these levels are considered to be within the range of acceptable value from an operationsconcept perspective. Figures C-3 through C-6 are computer generated antenna patterns for the 60, 46,33, and 23 foot antenna diameters. These figures were used to calculate the off-axis antenna gains atthe 3, 5, and 10-degree minimum elevation angles.

Table C-4. SATOPS Model Inputs

Antenna off-axis gain(dBi)

Effective IsotropicRadiated Power (EIRP)

(dBm)Terminal

TX Powers(watts)

AntennaDiameter

(ft) 3º 5º 10º 3º 5º 10ºCTS 2.25K max/100 min 33 8 5 3 72/58 69/55 67/53

NHS10K max/100 min2.5K max/100 min1K max/100 min

60 (A)46 (B)

33 (DLT)

24188

1755

1233

91/7182/6868/58

87/6769/5565/55

82/6267/5363/53

OAS 2000 max/100 min 51 (DLT) 18 5 3 81/68 68/55 66/53EVCF 2.25K max/100 min 23 23 16 12 87/73 80/66 76/62

(A), (B), and (DLT – Data Link Terminal) are designators used to differentiate between unique site locations.

IMT 2000 Assessment

C-6

Figure C-3. Computer Generated Antenna Pattern for the Automated Remote TrackingStation (ARTS) 60-foot Antenna Diameters

Angle (Degrees)

0 10 20 30 40 50 60 70 80 90 100 110 120 130 140 150 160 170 180

ARTS 60' Antenna: Gain vs. Angle

Gai

n (d

B)

-50

-40

-30

-20

-10

0

10

20

30

40

50

Feed and SparBlockage

SparScattering

Peak Gain = 49.3 dBFreq = 1.8 GHzRange = 2.5 MilesFar-Field = 2.5 Miles Prime Fed Paraboloid:Inclues feed blockageand secondary spar blockage and scattering.

RaytrackParabolas:Arts60a.fArts001005f.pgwTime: Thu Oct 05 16:16:39 2000

IMT 2000 Assessment

C-7

Figure C-4. Computer Generated Antenna Pattern for the 46-foot Antenna Diameters

ARTS 46' Antenna: Gain vs. Angle

-40

-30

-20

-10

0

10

20

30

40

50

Gai

n (d

B)

0 10 20 30 40 50 60 70 80 90 100 110 120 130 140 150 160 170 180

Angle (Degrees)

Peak Gain = 47.0 dBFreq = 1.8 GHzRange = 7.3 MilesFar-Field = 1.5 Miles

RaytrackCassegrains:Arts46b.fArts001003d.pgw

Time: Tue Oct 03 12:12:27 2000

IMT 2000 Assessment

C-8

Figure C-5. Computer Generated Antenna Patterns for the 33-Foot Antenna Diameters

33 Ft. Cassegrain Antenna: Gain vs. Angle

-40

-30

-20

-10

0

10

20

Gai

n (d

B)

30

40

50

Angle (Degrees)

0 5 10 15 20 25 30 35 40 45 50 55 60

Range (Miles)

R = 0.5

R = 5.0

Frequency = 1.8 GHzFar-Field = 0.75 Miles

RaytrackCassegrains:Rh33ft1.fRh33ft001002d.pgwIGRID=3, WLAMBDA=1.0

Time: Tue Oct 03 12:49:29 2000

IMT 2000 Assessment

C-9

-30

-20

-10

0

10

20

30

Gai

n (d

B)

40

50

Angle (Degrees)

0 10 20 30 40 50 60 70 80 90 100 110 120 130 140 150 160 170 180

Datron 23' Antenna: Gain vs. Angle

Freq = 1.8 GHzPeak Gain = 40.7 dBRange = 0.4 MilesFar-Field = 0.4 Miles Prime Fed Paraboloid:Includes feed blockageand secondary sparblockage and scattering

SparScattering

Time: Fri Oct 06 16:12:44 2000

RaytrackParabolas:Dia23ft1.fDia23ft001006d.pgw

Figure C-6. Computer Generated Antenna Patterns for the 23-Foot Antenna Diameters

IMT 2000 Assessment

C-10

C.4 RESULTS

Results of the signal level predictions for the four sites analyzed: CTS, NHS, OAS, and EVCF arecontained in Attachment 1. Three-dimensional topographic displays of the regions surrounding thesites are included to illustrate the relationship between terrain and predicted received signal level.Several plots are included within this section for discussion. A legend in the upper right corner of theoverlays defines the IMT-2000 received threshold plotted. It should be noted that the –121 dBmthreshold, which is depicted as white in the legend, is portrayed as yellow on the overlays. Below thelegend are all of the input parameters used to generate the overlay.

Figure C-7 is an overlay for the worst-case conditions at NHS: maximum transmitter power (10 kW),and minimum elevation angle (3 degrees). Worst case overlay conditions apply to the IMT-2000 basestations vice the mobiles due to the increased antenna height (40 meters) and higher antenna gain(17 dBi) associated with the fixed sites. As shown in the figure, no region within the 70 X 70 km areashown meets the -121 dBm threshold. In fact, virtually all of the area depicted in the overlayexperiences levels in excess of –71 dBm, well in excess of what might be considered a reasonablethreshold level for the IMT-2000 receivers. Figure C-8 depicts the coverage for the same site underbest case transmitter conditions, 100 watt transmitter power, and a 10-degree minimum elevationangle. While there is a noted reduction in the region exposed to levels in excess of –71 dBm, there isstill no area that meets or even approaches the -121 dBm threshold specified. Figure C-9 depicts thebest case overall (from an interference perspective) in that it depicts signal levels to a mobile receiver(reduced antenna height and antenna gain) at the lowest SATOPS transmit power and highest antennaelevation angle. Under these conditions, significant improvement is noted from the previous overlays;however, there are still significant portions that extend out 70 km and beyond from the site that exceedthe -105 dBm threshold.

IMT 2000 Assessment

C-11

Figure C-7. NHS-A, Antenna Elevation Angle: 3°, Transmitter Power: 10,000 W, IMT-2000Base Station

Figure C-8. NHS-A, Antenna Elevation Angle: 10°, Transmitter Power: 100 W, IMT-2000Base Station

IMT 2000 Assessment

C-12

Figure C-9. NHS-A, Antenna Elevation Angle: 10°, Transmitter Power: 100 W, IMT-2000Mobile Station

A review of the other sites analyzed produces similar results. Figure C-10 represents worst-caseSATOPS uplink conditions (maximum power, low elevation angle) for the OAS site. Like the NHSoverlays, signals in excess of -71 dBm extend well beyond 70 km from the uplink terminal. Underthese conditions, electromagnetic interference (EMI) from OAS extends well beyond the highlypopulated and highly desirable market regions of Oakland and San Francisco. Even under best caseconditions (10 degrees and 100 watts), Figure C-11 illustrates that the areas in excess of -121 dBmextend well over 75 km from the site. Figure C-12 depicts impact to IMT-2000 mobile users underbest case SATOPS uplink conditions. Like the NHS case, this represents the smallest potentiallyaffected area. However, the region impacted still encompasses highly desirable regions from an IMT-2000 market perspective.

IMT 2000 Assessment

C-13

Figure C-10. OAS, Antenna Elevation Angle: 3°, Transmitter Power: 2,000 W, IMT-2000Base Station

Figure C-11. OAS, Antenna Elevation Angle: 10°, Transmitter Power: 100 W, IMT-2000Base Station

IMT 2000 Assessment

C-14

Figure C-12. OAS, Antenna Elevation Angle: 10°, Transmitter Power: 100 W, IMT-2000Moblie Station

It should be noted that the assessment assumes 360-degree coverage for the SATOPS antenna. Whilefor many sites this is true (including NHS), there are some sites that do concentrate activities withinspecific azmiuth ranges. A follow-on effort to generate overlays that reflect more of the operationsconcepts for the sites would be beneficial. It is also worthy of note that a particular SATOPS uplinkterminal only transmits on one channel at a time thereby lessening the impact to IMT-2000 users onadjacent operating frequencies. This fact, coupled with the specific antenna azimuth operations, allowsfor the possibility of sharing on a time/frequency basis.

C.5 BAND SEGMENTATION

Band segmentation schemes have been proposed that would separate Government use and IMT-2000use into separate portions of the 1760-1850 MHz band. One such proposal is to allow SATOPSfunctions in the 1760-1805 MHz band and IMT-2000 operations in the 1805-1850 MHz band. Sucha proposal serves to minimize the potential for electromagnetic interference (EMI) by maintaining afrequency separation between transmitters and receivers. Given that SATOPS functions currentlysupport satellites operating throughout the 1761-1842 MHz band, a segmentation scheme alonewould reduce but not eliminate the potential for EMI to IMT-2000 receivers. The potential for EMI

IMT 2000 Assessment

C-15

would remain for those systems operating in the IMT-2000 portion of the spectrum until therequirement to support such satellites no longer existed. In some instances however, satelliteprograms are supported via two S-band channels. This introduces the added benefit of frequencyflexibility and provides an EMI mitigation possibility if one of the two channels lies outside the IMT-2000 spectrum. Finally, for those satellites that have not yet been launched, the opportunity exists tooutfit the vehicle with SATOPS transponders in the band segment allocated for TT&C.

To illustrate the impact of off-tuning the SATOPS uplink and IMT-2000 receivers on the relative sizeof the coordination regions, three sample overlays were generated for the New Hampshire B terminaloperating at 2.5 kilowatts with a 10 degrees elevation angle. Figures C-13 through C-15 illustrate thecoordination regions for IMT-2000 base station receivers assuming frequency separations of 4, 8, and12 MHz respectively (1, 2, and 3 SATOPS uplink channels). Beyond 12 MHz, the uplink emissionrolls off gradually such that additional frequency separation yields minimal benefit.

Figure C-13. Coordination Overlay for 4-MHz Frequency Separation

IMT 2000 Assessment

C-16

Figure C-14. Coordination Overlay for 8-MHz Frequency Separation

IMT 2000 Assessment

C-17

Figure C-15. Coordination Overlay for 12-MHz Frequency Separation

As can be viewed from the overlays, frequency separation clearly reduces the coordination regions,however, like other mitigation techniques discussed, it does not singly provide sufficient isolationbetween the systems to eliminate the potential for EMI. The limited benefit achieved through off-tuning is reflective of the typically wide/unfiltered emission spectra in the current SGLS signalstructure, which is in part due to the unwanted spectral components generated via a class C amplifier.It is expected that the more spectrally efficient signal structures that are being considered for futureSATOPS uplinks would yield greater benefit in a band segmentation scheme.

C.6 CONCLUSIONS

SATOPS uplink power management, antenna elevation angle restrictions, and frequency off tuninghelp to reduce the affected area around the SATOPS uplink transmitter. However, if coordination

IMT 2000 Assessment

C-18

regions on the order of 10 to 20 km are desired, and IMT-2000 specified interference thresholds are tobe met, an orders of magnitude decrease in the undesired signal level will be required. Additionalmeasures for reducing the uplink power at the IMT-2000 receiver coupled with power managementand antenna restrictions must be implemented to significantly limit the affected area surrounding theuplink site.

C.7 SATOPS UPLINK TO IMT-2000 RECEIVERS INTERFERENCEMITIGATION MEASURES

Based upon the results of the signal level predictions, it is apparent that additional signal attenuationis required if sharing between the services is desired. Potential mitigation techniques fall into one ofthree categories: measures implemented solely by the DoD SATOPS community, measuresimplemented solely by the IMT-2000 industry, and those techniques that require mutualimplementation by both parties. The following measures are presented for discussion andconsideration. Further analysis is warranted to address viability, cost, and implementation issues.

C.7.1 DoD EMI Mitigation Techniques

C.7.1.1 Relocation of the SATOPS Uplink Antennas and/or SATOPS TransmissionOff-loading

Many of the current SATOPS terminals around the world are located in remote areas such as DiegoGarcia and Thule, Greenland. It is expected that these regions will have a relatively low IMT-2000user density. There are, however, several stations, such as New Hampshire or Sunnyvale, locatednear population centers. For sites such as these, it may be useful to consider moving the antennasthemselves to more remote locations with lower population densities that are less desirable from anIMT-2000 market perspective. Similarly, where satisfactory visibility can be achieved, it may bepossible that some of the operations currently performed by terminals in populated areas could be off-loaded to the more remote terminals. The signals to be radiated or received by these antennas couldbe fed to/from the stations by fiber optic or cable.

C.7.1.2 Reduction of the Out-of-Beam Energy of the SATOPS Antennas

Assuming that the mainbeam emissions are highly focused in the SATOPS antennas, some control ofthe radiation in the direction of the victim receivers would be beneficial. The most commonapproaches to this are (1) antenna elevation angle restrictions and (2) intentional signal blockage andantenna redesign.

IMT 2000 Assessment

C-19

SATOPS Antenna Elevation Angle Restrictions. Like power management, restricting theminimum elevation angle serves to limit the power at the horizon and hence reduce the undesiredsignal into the IMT-2000 receiver. As illustrated in the overlays, a 10-degree minimum elevationangle reduced the size of the affected areas. However, even when coupled with power management,these measures are insufficient to reduce EMI regions to expected acceptable levels. A study of theoperations impact for going to a 10-degree minimum elevation angle should be conducted. Whereacceptable, this limitation would serve to reduce the EMI potential and promote sharing.

Signal Blockage and Antenna Redesign. Intentional signal blockage can be achieved via acylinder surrounding the dish to reduce spillover, modification of the feed, or modification of theillumination taper to reduce sidelobes at the expense of gain.

The use of RF absorbing materials around struts and at the back of the antenna to reduce secondaryreflection would also help eliminate sidelobe emissions. Redesign of the antennas to a type such asan offset parabola, which has inherently lower sidelobes is also worthy of consideration. Apart fromthe antenna design and structure, radar fences, screening, and even the use of vegetation at the sitecan be effective measures to block emissions in specific directions. These and the other measuresdiscussed for controlling signals outside of the mainbeam are worth additional consideration to weighcost versus benefit.

C.7.1.3 SATOPS Power Management

SATOPS transmit power capabilities typically vary over a wide range from as low as 100 watts to asmuch as 10 kw. The high-power transmissions are typically reserved for anomalies but are alsoradiated periodically for system check-out and training. Link closure with adequate margin cantypically be achieved at powers in the 100 to 500 watt range. As indicated in the signal levelpredictions, power management does not in of itself solve the EMI problem; however, it does reducethe size of the affected regions. Follow-on studies should be performed to determine the minimumacceptable levels required for maintaining satisfactory link closure. Operations at these levels wouldbe one step toward reducing the EMI to IMT-2000 receivers.

C.7.2 IMT-2000 EMI Mitigation Techniques

C.7.2.1 Establishment of Keep-Out Zones

Short of complete frequency separation, there is a potential for EMI to a mobile user (or fixed basestation) if it is allowed to operate in proximity to an SATOPS uplink transmitter. The signal level

IMT 2000 Assessment

C-20

overlays clearly show the potential size of the affected areas. The possibility of some keep-out zone,even if only a few kilometers surrounding the site, should be considered to help mitigate the mostchallenging close in interactions.

C.7.2.2 Base Station Antenna Nulling

It is expected that IMT-2000 antenna implementation may be similar to the current cellular/PCSdesigns; three direction antenna segments each covering a 120 degree sector. This scheme introducesthe possibility to add an additional highly directive antenna in the direction of the SATOPS terminaland to use that signal to null out the received signals on the broadbeam antenna in the direction of theSATOPS terminal. The hole in coverage created by this scheme could then be filled via an alternateantenna at a location such that a mainbeam interaction with the SATOPS terminal is avoided.

C.7.2.3 Polarization Discrimination

Polarization discrimination mitigation takes advantage of the fact that the mobile signals are linearlypolarized, whereas the SATOPS uplinks are circularly polarized. By measuring the receivedpolarization and cross polarizing the IMT-2000 base station to that signal, a significant reduction ininterference is achievable (20 dB) with only a 3-dB reduction to the mobile signal. This proposalobviously requires an investment in technology by the IMT-2000 community and may be practical ona limited scale for base stations in specific problem areas.

C.7.3 Mutual EMI Mitigation Techniques

Cooperative scheduling is an attractive EMI mitigation technique that offers a potential benefit ifmutual agreement and coordination with the IMT-2000 industry can be achieved. Cooperativescheduling is not unlike band segmentation in that both approaches look toward frequency separationbetween the systems as a technique for minimizing the potential for EMI. Note however thesignificant distinction between cooperative scheduling, which assumes sharing of the entire SGLSuplink band via real-time frequency deconfliction, and band segmentation, which assumes separationof systems into distinctly separate portions of the spectrum. Unlike band segmentation, cooperativescheduling addresses EMI issues associated with uplinks to currently flying systems for which onlyone S-band channel is available for TT&C. In these instances, there is essentially no flexibility interms of spectrum use from the SATOPS perspective.

Cooperative scheduling takes advantage of the fact that SATOPS operations only use a limitedamount of spectrum at any given instant in time. That, coupled with the specific antenna pointingrequired for a satellite contact, limits the affects on the environment. Therefore, at any instant, only a

IMT 2000 Assessment

C-21

relatively small portion of the IMT-2000 network maybe affected. The concept behind cooperativescheduling is to allow the IMT-2000 network to dynamically assign spectrum usage to the networkaround the SATOPS uplink transmissions. This technique would require software enhancements anddynamic switching capabilities for the IMT-2000 systems. It also assumes that the IMT-2000switching algorithm is fed information on the SATOPS uplink schedule either in advance via pre-coordination, in real-time via landline, or by monitoring the environment for SATOPS signal use.The requirement to pass SATOPS scheduling information to IMT-2000 service providers in turnraises operations securities issues that need to be addressed. While this mitigation technique is notwithout its challenges, it takes advantage of the SATOPS unique time/frequency use of theelectromagnetic spectrum and, therefore, could be one of the more effective techniques to reduceEMI to the IMT-2000 users.

C.7.4 Summary

Further study is required to quantify the benefit of the aforementioned mitigation measures. FiguresC-16 and C-17 are provided to illustrate the benefit of mitigation techniques that provide anadditional 50 dB of attenuation in the direction of the victim receiver. Note that under the worst caseconditions for NHS, the affected area improvement is notable but still considerably large. Bycontrast, the coordination area for the NHS DLT under best case conditions (10 degrees and 100watts) is reduced to only a very few small regions local to the uplink site.

IMT 2000 Assessment

C-22

Figure C-16. NHS-A, Antenna Elevation Angle: 3°, Transmitter Power: 10,000 W, IMT-2000Base Station, Plus an Additional 50 dB of Signal Attenuation

Figure C-17. NHS-DLT, Antenna Elevation Angle: 10°, Transmitter Power: 100 W,IMT-2000 Mobile Station, Plus an Additional 50 dB of Signal Attenuation

IMT 2000 Assessment

D-1

APPENDIX D – POTENTIAL FOR SHARING BETWEENIMT-2000 AND TACTICAL RADIO RELAY IN THE1755-1850 MHZ FREQUENCY BAND

A large number of existing Department of Defense (DoD) line-of-sight (LOS) microwave (MW)

systems operate in the 1755-1850 MHz frequency band. This appendix addresses the potential for

interference between the IMT-2000 systems and the DoD tactical radio relay systems.

The LOS MW systems operating in the band are too numerous to analyze individually, and many of

these systems do not have unique requirements limiting the systems to frequencies below 3 GHz.

However, one class of systems with requirements constraining operations to frequencies near the

1755-1850 MHz band are the DoD tactical radio relay systems, and these systems were analyzed in

the assessment.

The military services require efficient methods of exchanging large quantities of digital data

throughout the battlefield. The increased use of computers, digital video, and facsimile equipment in

command and control, intelligence, and logistics will generate more data in the future. The military

radios are deployable, point-to-point radio systems using low-to-moderate gain antennas. The

military tactical radio relay equipment uses broad beamwidth antennas for quick link setup during

deployments. The movement of the lightweight, flexible masts that support the antennas or the

movement of shipboard antennas preclude the use of narrowbeam antennas. The requirements for

low/moderate power levels for the transportable radios and the broad beamwidth antenna limits

applicable frequency band to below 3 GHz. The primary DoD tactical radio relay systems operating

in the 1755-1850 MHz band are the US Army Mobile Subscriber Equipment (MSE) and the US Navy

Digital Wideband Transmission System (DWTS).

D.1 ANALYSIS APPROACH

The DoD tactical radio relay systems potential for sharing the 1755-1850 MHz frequency band with

the IMT-2000 systems was investigated on a one-to-one basis. A distance separation required to

protect each of four radio relay systems from each of the four candidate IMT-2000 systems and each

of the four candidate IMT-2000 systems from the four radio relay systems was determined. The

IMT-2000 mobiles and base stations (including main-beam and side-lobe antenna gains) were

analyzed versus the radio relay main-beam and side-lobe antenna gains. The ship-based DWTS uses

an omnidirectional antenna, and the DWTS was analyzed at the highest and lowest transmitter power

setting.

IMT 2000 Assessment

D-2

D.2 TACTICAL RADIO RELAY SYSTEM DESCRIPTIONS

MSE. The MSE is a multi-band, tactical LOS radio system, more accurately described as a “system-

of-systems,” because it is composed of several components, each of which are fully operational

systems. The individual components that make up the MSE are dependent upon several portions of

the radio frequency spectrum (e.g., 30-88 MHz, 225-400 MHz, 1350-1850 MHz, and

14.5-15.35 GHz). The inability of any of these components to operate successfully would result in

the failure of the overall system. One critical component of the MSE, the AN/GRC-226(V)2 radio,

operates in the 1755-1850 MHz frequency band. It is used to connect radio access units to the node

center switch of the network. Operational use plans call for 465 units per Army Corps, giving a total

of 2,325 units for five Corps. The AN/GRC-226(V)2 is a digital radio that can tune to any of 4000

available channels, spaced at 125 kHz, between 1350-1850 MHz; however, due to the allocation of

most of this band to other services, users rarely have access to spectrum outside of 1350-1390 MHz

and 1710-1850 MHz. The AN/GRC-226(V)2 requires a 50.125-MHz minimum frequency separation

between the site transmitter and receiver for a duplex link. The technical parameters of the AN/GRC-

226(V)2 used in the analysis are presented in Table D-1.

Table D-1. AN/GRC-226 (V) Parameters (J/F 12/6102/2)Frequency range 1350 – 1850 MHzTransmit power 0.5 - 5 W

Emission Bandwidth (MHz)a 1.25 (-3dB), 3.5 (-20dB), 10.55 (-60dB)Antenna gain 20 dBi (MB), 11 dBi (20-90 deg), 2 dBi (90-180 deg)

Antenna height 30 mReceiver bandwidth (MHz)a 0.85 (-3dB), 1.6 (-20dB), 4.4 (-60dB)

Receiver noise figure 8 dBReceiver sensitivity -93 dBm @ BER = 10E–5 (S/N = 14 dB)

Receiver noise power -107 dBmInterfering signal threshold -113 dBm

Cable losses 2.4 dB (NPT calc)Waveform 2M40F9W*, 256 – 2048 kbps MSK

a2048 kbps

HCLOS. The High Capacity LOS (HCLOS) radio system is expected to eventually replace the

AN/GRC-226(V)2 radios in the MSE for the Area Common User System (ACUS). The HCLOS

radio, the AN/GRC-245(V), operates in the 225-400 MHz and 1350-2690 MHz bands with increased

spectral efficiency and higher data rates compared to the current radio. The AN/GRC-245(V) requires

a 50.125-MHz minimum frequency separation between the site transmitter and receiver for a duplex

link. The technical parameters of the AN/GRC-245(V) used in the assessment are presented in

Table D-2.

IMT 2000 Assessment

D-3

Table D-2. AN/GRC-245 (V) Parameters (J/F 12/7601)Frequency range 1350 – 2690 MHzTransmit power 31 mW - 1.6 W

Emission Bandwidth (MHz)a 2.0 (-3dB), 2.9 (-20dB), 7.2 (-60dB)Antenna gain 23 dBi (mainbeam)

Antenna height 30 mReceiver bandwidth (MHz)a 6.7 (-3dB), 8.1 (-20dB), 10.0 (-60dB)

Receiver noise figure 7 dBReceiver sensitivitya -86 dBm @ 8192 Kb/s and BER = 10E-5

Receiver noise powera -99 dBmInterfering signal thresholda -105 dBm

Cable losses 4 dB @ 1850 MHzWaveform 2M50W1D**,320-8256 kb/s, 32 TCM, rate 4/5 code

a8256 kbps

DWTS. The DWTS is a LOS tactical radio system providing point-to-point (shore based AN/MRC-

142), ship-to-ship (ship based AN/SRC-57) and ship-to-shore (AN/SRC-57 and AN/MRC-142 or the

Army AN/GRC-226) communications. The DWTS provides communications vital to the

Commander Joint Task Force (CJTF), Commander Amphibious Task Force (CATF), Commander

Landing Force (CLF), Amphibious Forces afloat, and US Forces ashore. The system provides afloat

and ashore commanders with entry into the Global Command and Control System – Maritime

(GCCS-M) to ensure common access to intelligence, mapping, order of battle, and logistics

information. The DWTS provides data transmissions for Battlegroup (BG) planning, video tele-

conferences, BG e-mail connectivity, internet connectivity and intra-BG telephone connectivity.

DWTS provides tactical digital wideband transmissions for voice, video, and data to support landing

force command elements to include Marine regiment or Expeditionary Unit and higher and Army

brigade and higher. The DWTS consists of two components, the shore based USMC AN/MRC-142

and the ship based US Navy AN/SRC-57.

AN/MRC-142. The shore based component of the DWTS, the AN/MRC-142, typically uses the

frequency bands 1350-1390 MHz, 1432-1435 MHz, and 1710-1850 MHz. In addition, the AN/MRC-

142 ship-to-shore links have further frequency restrictions caused by ship-based interference to the

AN/SRC-57 located on ships. The AN/MRC-142 requires a 62-MHz minimum frequency separation

between the site transmitter and receiver for a duplex link. The technical parameters of the

AN/MRC-142 used in the evaluation are presented in Table D-3.

IMT 2000 Assessment

D-4

Table D-3. AN/MRC-142 Parameters (J/F 12/6461)Frequency range 1350 – 1850 MHzTransmit power 3.0 W

Emission Bandwidth (MHz) 0.4 (-3dB), 1.05 (-20dB), 3.15 (-60dB)Antenna gain 20 dBi (mainbeam), 6.3 dBi (26 deg)

Antenna height 30 mReceiver bandwidth (MHz) 0.8 (-3dB), 1.0 (-40 dB), 4.4 (-60 dB)

Receiver noise figure 8 dBReceiver sensitivity -93 dBm BER = 10E-4

Receiver noise power -107 dBmInterfering signal threshold -113 dBm

Waveform 610K0F7W, 576kbps FSK

AN/SRC-57. The ship-based AN/SRC-57 uses an omnidirectional antenna to communicate with

other ships and shore-based radios. The AN/SRC-57 can tune over the 1350-1850 MHz frequency

band for operations in international waters. However, operations close to the continental US

(CONUS) restrict the frequencies of operations to 1350-1390 MHz, 1432-1435 MHz, and

1710-1850 MHz. The AN/SRC-57 can experience shipboard interference interactions that could

eliminate additional frequency bands. The AN/SRC-57 can receive interference from shipboard

systems such as the TAS MK 23 radar, AN/SPS-49 radar, and INMARSAT and can cause

interference to GPS, INMARSAT, and AN/SMQ-11 Weather Satellite Receivers.

The AN/SRC-57 requires a 50-MHz minimum frequency separation between the site transmitter and

receiver for ship-to-ship duplex links; however, ship-to-shore links must conform to the 62 MHz

separation requirements of the AN/MRC-142. The technical parameters of the AN/SRC-57 used in

the assessment are presented in Table D-4.

Table D-4. AN/SRC-57 Parameters (J/F 12/7652)Frequency range 1350 – 1850 MHzTransmit power 5 – 250 W

Emission Bandwidth (MHz) 1.0 (-3dB), 3.0 (-20 dB), 8.0 (-60 dB)Antenna gain 1.5 dBi Omni

Antenna height 30 mReceiver bandwidth (MHz) 1.6 (-3 dB), 4.0 (-20 dB), 9.2 (-60 dB)

Receiver noise figure 7 dBReceiver sensitivity -84 dBm BER = 10E-5

Receiver noise power -105 dBmInterfering signal threshold -111 dBm

Waveform 2M85F7D, 144-2304 Kb/s binary FSK

D.3 ASSESSMENT

The technical parameters for the tactical radios (see the System Description section) were obtained

from the Spectrum Certification Applications and from data provided by the program manager for

IMT 2000 Assessment

D-5

each radio. The technical parameters for the IMT-2000 radios used in the sharing assessment are

presented in a previous section of this report. The interference threshold values of the IMT-2000

CDMA system receivers are referenced to the data rate of the CDMA modulation. The interference

threshold referenced to the receiver bandwidth would be increased by the ratio of the receiver

bandwidth to the data rate. The revised interference thresholds (It) are presented in Table D-5.

Table D-5. CDMA-2000 Receiver Interference ThresholdsCDMA-2000 NB (1.25 MHz) CDMA-2000 WB (3.75 MHz)Base Mobile Base Mobile

InterferenceThreshold 1

-114.6 dBm -110.6 dBm -109.9 dBm -105.9 dBm

InterferenceThreshold 2

-99.1 dBm -95.1 dBm -94.4 dBm -90.4 dBm

The interference thresholds for the DoD tactical radio receivers were based on the Recommendation

ITU-R F.1334, which limits the degradation due to interference in the fixed service receiver to 1 dB.

This value corresponds to an allowed interference-to-noise power ratio (I/N) of –6 dB. Also, for one

example, an additional, higher threshold was used, assuming a desired signal level of –75 dBm, and

an S/(I+N) of 14 dB.

The analysis was performed to identify the required distance separation to protect the tactical radio

relay receivers from the IMT-2000 transmitters and the IMT-2000 receivers from the tactical radio

relay transmitters. The required propagation loss was calculated using transmitter powers, transmitter

and receiver antenna gains, frequency-dependent rejection, and the receiver interference threshold as

follows:

LP = PT + GT + GR + LS – FDR – IT (D-1)

where:

LP = required propagation path loss to preclude interference (dB)

PT = output power of the source transmitter (dBm)

GT = source transmit antenna gain in the direction of the victim receiver (dBi)

GR = victim receive antenna gain in the direction of the source transmitter (dBi)

LS = transmitter and receiver line losses (dB)

FDR = frequency-dependent rejection (dB)

IT = receiver interference threshold (dBm).

The Spherical Earth Model (SEM) was used to determine the required distance separation to preclude

interference. The SEM is applicable to paths over a smooth, spherical, homogenous, and imperfectly-

conducting earth. The dominant mode of propagation can be either LOS, diffraction, or tropospheric

IMT 2000 Assessment

D-6

forward-scatter. The SEM calculates the required distance separation based on the required

propagation loss, link frequency, and transmitter/receiver antenna heights.

The above assessment was used to evaluate the frequency separation versus distance separation

requirements for one sample case of the AN/GRC-226 and the CDMA WB (3.75 MHz). The

receiver selectivity and the transmitter emission spectrum were off-tuned, and the FDR was

determined for several values of frequency separation.

D.4 RESULTS

The IMT-2000 to tactical radio relay distance separation requirements are presented in Table D-6, the

tactical radio relay to IMT-2000 (minimum interference threshold) distance requirements are

presented in Table D-7, and the tactical radio relay to IMT-2000 (more typical interference threshold)

distance separation requirements are presented in Table D-8.

Table D-6. IMT-2000 to Tactical Radio Relay Distance Separation RequirementsCo-Channel Operation

Interference Path CDMA NB CDMA WB IS-136 GSMSource Victim Distance (Km) Distance (Km) Distance (Km) Distance (Km)

IMT-2000 Base GRC-226 MB 87.1 78.1 91.9 91.1IMT-2000 Base GRC-226 SL 63.9 60.7 65.5 65.2

IMT-2000 Base SL GRC-226 SL 52.3 49.0 53.9 53.7IMT-2000 Mobile GRC-226 MB 22.5 19.8 23.8 23.6IMT-2000 Mobile GRC-226 SL 11 9.2 11.9 11.8

IMT-2000 Base GRC-245 MB 75.2 74.7 75.5 75.5IMT-2000 Base GRC-245 SL 56.8 56.5 57.0 57.0

IMT-2000 Base SL GRC-245 SL 45.0 44.6 45.1 45.1IMT-2000 Mobile GRC-245 MB 18.8 18.5 19.0 19IMT-2000 Mobile GRC-245 SL 7.4 7.2 7.5 7.5

IMT-2000 Base MRC-142 MB 85.5 75.7 91.9 91.1IMT-2000 Base MRC-142 SL 63.4 59.8 65.5 65.2

IMT-2000 Base SL MRC-142 SL 51.8 48.0 53.9 53.7IMT-2000 Mobile MRC-142 MB 22.0 19.0 23.8 23.6IMT-2000 Mobile MRC-142 SL 10.7 8.7 11.9 11.8

IMT-2000 Base SRC-57 62.0 59.0 63.3 63.1

IMT-2000 Base SL SRC-57 50.3 47.2 51.7 51.5IMT-2000 Mobile SRC-57 10 8.4 10.6 10.5

IMT 2000 Assessment

D-7

Table D-7. Tactical Radio Relay to IMT-2000 Distance Separation RequirementsCo-Channel Operation

Minimum Interference Threshold Interference Path CDMA NB CDMA WB IS-136 GSM

Source Victim* Distance (Km) Distance (Km) Distance (Km) Distance (Km)

GRC-226 MB IMT-2000 Base 82 75.4 85.0 84.2GRC-226 SL IMT-2000 Base 62.2 59.6 63.2 62.9GRC-226 SL IMT-2000 Base SL 50.5 47.9 51.6 51.3GRC-226 MB IMT-2000 Mobile 34 31.5 35.0 34.7GRC-226 SL IMT-2000 Mobile 19.5 17.5 20.4 20.2

GRC-245 MB IMT-2000 Base 73.7 71.9 75.2 74.1GRC-245 SL IMT-2000 Base 55.4 53.5 56.1 55.9GRC-245 SL IMT-2000 Base SL 43.5 41.6 44.3 44.1GRC-245 MB IMT-2000 Mobile 30.0 28.3 30.7 30.5GRC-245 SL IMT-2000 Mobile 14.5 13.3 15.0 14.9

MRC-142 MB IMT-2000 Base 81.3 73.6 91.4 90.5MRC-142 SL IMT-2000 Base 61.9 58 65.6 65MRC-142 SL IMT-2000 Base SL 50.2 46.2 54.1 53.5MRC-142 MB IMT-2000 Mobile 33.7 29.9 37.4 36.8MRC-142 SL IMT-2000 Mobile 19.4 16.3 22.5 21.9

SRC-57 HP IMT-2000 Base 79.8 74.0 83.5 82.7SRC-57 LP IMT-2000 Base 62.2 59.3 63.6 63.3SRC-57 HP IMT-2000 Base SL 65.7 62.9 67.0 66.8SRC-57 LP IMT-2000 Base SL 50.6 47.6 52.0 51.7SRC-57 HP IMT-2000 Mobile 33.2 30.3 34.5 34.2SRC-57 LP IMT-2000 Mobile 19.6 17.3 20.7 20.5

*Desired signal at sensitivity, I/N = - 6 dB

IMT 2000 Assessment

D-8

Table D-8. Tactical Radio Relay to IMT-2000 Distance Separation RequirementsCo-Channel Operation

For the minimum interference threshold case, the distance separation requirements between the

tactical radio relay and the IMT-2000 base stations would be approximately 92 km if random antenna

orientations were allowed for both systems. With the same interference threshold, the distance

separation requirements between the tactical radio relay and the IMT-2000 base stations would be

approximately 55 km if side-lobe antenna orientations were constrained for each system toward the

other system (assumes low-power operation for the AN/SRC-57).

With the minimum interference threshold, the distance separation requirements between the tactical

radio relay and the IMT-2000 mobiles would be approximately 38 km if random antenna orientations

were allowed for the tactical radio relay. If tactical radio relay main-beam antenna orientations

(assumes low-power operation for the AN/SRC-57) were constrained away from areas of IMT-2000

operations and IMT-2000 mobiles were restricted from some areas of operations, the distance

separation requirements would be approximately 23 km. The above distance separation requirements

cannot be accommodated in many areas of tactical radio relay operations in the US.

Typical Interference ThresholdInterference Path CDMA NB CDMA WB IS-136 GSM

Source Victim* Distance (Km) Distance (Km) Distance (Km) Distance (Km)

GRC-226 MB IMT-2000 Base 64.3 61.8 65.4 65.1GRC-226 SL IMT-2000 Base 48.2 45.6 49.3 49.0GRC-226 SL IMT-2000 Base SL 36.2 33.6 37.4 37.1GRC-226 MB IMT-2000 Mobile 21.3 19.2 22.2 22.0GRC-226 SL IMT-2000 Mobile 10.2 8.9 10.8 10.7

GRC-245 MB IMT-2000 Base 60.3 58.4 61.0 60.8GRC-245 SL IMT-2000 Base 41.2 39.3 42.0 41.8GRC-245 SL IMT-2000 Base SL 29.3 27.4 30.0 29.8GRC-245 MB IMT-2000 Mobile 18.1 16.7 18.6 18.5GRC-245 SL IMT-2000 Mobile 7.0 6.2 7.3 7.2

MRC-142 MB IMT-2000 Base 64.1 60.2 67.8 67.2MRC-142 SL IMT-2000 Base 47.9 43.9 51.8 51.2MRC-142 SL IMT-2000 Base SL 36.0 31.9 39.9 39.3MRC-142 MB IMT-2000 Mobile 21.1 18.0 24.4 23.8MRC-142 SL IMT-2000 Mobile 10.1 8.1 12.3 11.9

SRC-57 HP IMT-2000 Base 63.6 60.7 64.9 64.6SRC-57 LP IMT-2000 Base 48.3 45.3 49.7 49.4SRC-57 HP IMT-2000 Base SL 52.0 48.9 53.3 53.0SRC-57 LP IMT-2000 Base SL 36.3 33.3 37.7 37.5SRC-57 HP IMT-2000 Mobile 20.7 18.3 21.8 21.6SRC-57 LP IMT-2000 Mobile 10.3 8.7 11.0 10.9

*Desired Signal 10 dB above sensitivity and BER = 10E-3

IMT 2000 Assessment

D-9

For one example interaction, the distance separation requirements were also determined for the case

of a tactical radio relay link with a typical received signal level. The example uses CDMA WB (3.75

MHz) interference to an AN/GRC-226 receiver. The AN/GRC-226 link with an elevated site

location and favorable weather parameters could receive a faded desired signal level of -75 dBm with

a corresponding interference threshold of -89 dBm, for an S/(I+N) = 14 dB. The required distance

separation values for this example are presented in Table D-9.

If a an interference threshold for a typical received signal level (approximately 10 dB above receiver

sensitivity for the IMT-2000 or -75 dBm for the AN/GRC-226) is used, the separation requirements

are 68 km and 40 km for random antenna orientations (main-beam) and side-lobe antenna

orientations, respectively. These less conservative separation distances would still be difficult

implement at most tactical radio relay operations areas.

The frequency separation verses distance separation requirements for one sample case of the

AN/GRC-226 and the CDMA WB (3.75 MHz) are presented in Table D-10. The frequency

separation was limited to 5 MHz because data was not available on the IMT-2000 systems that are

under development. These preliminary calculations indicate that separation distances of 34.5 km are

required for one channel separation (5MHz) between the AN/GRC-226 and the CDMA WB (3.75

MHz) base station.

Table D-9. CDMA-2000 NB (1.25 MHz) to AN/GRC-226Co-Channel Operation

Interference Path Source Transmitter Data Victim Receiver Data FDRPath Loss Distance

Source Victim Power Antenna TX Cable Int Thresh Antenna RX Cable SEMdBm dBi dB dBm dBi dB dB dB Km

CDMA NB Base GRC-226 MB 40 15 1 -89 20 2.4 1.8 158.8 58.6CDMA NB Base GRC-226 SL 40 15 1 -89 2 2.4 1.8 140.8 42.2

CDMA NB Base SL GRC-226 SL 40 2 1 -89 2 2.4 1.8 127.8 30.3CDMA NB Mobile GRC-226 MB 20 0 0 -89 20 2.4 1.8 124.8 8.2CDMA NB Mobile GRC-226 SL 20 0 0 -89 2 2.4 1.8 106.8 3.0

IMT 2000 Assessment

D-10

Table D-10. Frequency Verses Distance Separation Requirements for theAN/GRC-226 and the CDMA-2000 WB (3.75 MHz)

Interference Path Off-tuning SeparationDistance

Source Victim MHz KmGRC-226 MB CDMA WB Base 0 75.3

1.0 75.32.0 70.63.0 58.34.0 45.65.0 34.5

CDMA WB Base GRC-226 MB 0 78.11.0 75.32.0 69.93.0 55.74.0 20.55.0 16.4

D.5 CONCLUSIONS

The full band sharing of the 1755-1850 MHz frequency band by the IMT-2000 and transportable

tactical radio relay does not appear feasible based on the current projections of the IMT-2000

configuration. The IMT-2000 base station to tactical radio relay distance separation requirements

(based on I/N = -6 dB) of 92 km (main-beam to main-beam) to 55 km (side-lobe to side-lobe) cannot

be satisfied at many locations with tactical radio relay operations. Even if a less conservative

interference threshold is used (sensitivity +10 dB for the IMT-2000 and -75 dBm for the AN/GRC-

226), the IMT-2000 and tactical radio relay receivers still require 68 km and 40 km of separation.

D.6 MITIGATION TECHNIQUES

There are several mitigation techniques which should be explored to reduce the distance separation

requirements and allow band sharing as follows:

• Investigate segmenting the 1755-1850 MHz frequency band; however, segementation of the

1755-1850 MHz frequency band may result in spectrum spillover into adjacent bands.

• Identify cross-polarization between IMT-2000 base stations and the tactical radio relay can

reduce the level of interference interactions.

IMT 2000 Assessment

E-1

APPENDIX E – POTENTIAL FOR INTERFERENCEBETWEEN IMT-2000 ENVIRONMENT AND AIR COMBATTRAINING SYSTEMS (1755-1850 MHZ)

The 1755-1850 MHz frequency band is used by Air Combat Training Systems (ACTS) such as the Air

Force’s Air Combat Maneuvering Instrumentation (ACMI) and the identical Navy Tactical Aircrew

Combat Training System (TACTS). These existing ACTS systems transmit data to the aircraft on either

1830 or 1840 MHz and receive data from the aircraft on either 1778 MHz or 1788 MHz. Ranging tones

and 198.4 kbps data, using frequency shift keying, are transmitted. Point-to-point links in this band are

also used to communicate the data from remote sites to a central location.

In the future, the Joint Tactical Combat Training System (JTCTS) is scheduled to replace the existing

ACTS. The JTCTS data links also operate air-to-ground, ground-to-air, and ground-to-ground, and can

tune across the band 1710-1850 MHz in 5 MHz increments. The JTCTS data link signal structure is l6-

ary, orthogonal signaling, with 0.351, 0.703, and 1.406 kbps data rates combined with either 5.63 or

22.5 Mchips/s pseudorandom spreading codes.

This appendix addresses the possible interference between IMT-2000 base and mobile stations and the

ACTS, also described as the TACTS/ACMI and the JTCTS operating in the frequency band 1755-1850

MHz.

E.1 SYSTEM DESCRIPTIONS

Technical characteristics of the TACTS/ACMI and JTCTS, together with relevant operational

assumptions, are given in the following paragraphs.

E.1.1 TACTS/ACMI Characteristics

E.1.1.1 System Characteristics

Characteristics of the TACTS/ACMI system are given in Tables E-1, E-2, and E-3. Values are those in

the frequency allocation applications,1,2,3,4 unless noted otherwise. Certain parameters of the internal

1Application for Equipment Frequency Allocation (DD Form 1494) for AN/TSQ-T4 Master Station and subsequent

Notes to Holders, J/F 12/4321, Washington, DC: MCEB, April 1975.

IMT-2000 Assessment

E-2

AIS units were not available. The values were estimated based on the corresponding parameters of the

AIS pod units, and these parameters are indicated by the shaded cells of Tables E-1 and E-2. For

transmitter emission bandwidths and receiver IF bandwidths, as well as harmonic and spurious levels,

the DD Form 1494 values were used instead of the specified values.5 It was felt the specified values

represented a limit not to be exceeded, while the 1494 values more closely represented actual system

characteristics. TACTS/ACMI frequencies and the link types associated with their use are listed in

Table E-4.

E.1.1.2 Operational Considerations

In an earlier analysis for the Air Force Frequency Management Agency (AFFMA),6 ground-to-air

separation distances of 78 and 35 km were used. These values correspond to 48.5 mi (42.1 nmi) and

21.75 mi (18.9 nmi) respectively. The specified nominal maximum range appears to be 65 nmi.7 The

separation distances of 78 km (42.1 nmi) and 35 km (18.9 nmi) were used in the TACTS/ACMI portion

of this analysis.

The maximum number of aircraft is stated to be 36 (Reference 7). In this analysis, the effect of the

number of aircraft flying at a given time was not considered.

Altitudes of 5000 m (16,400 ft) and 9000 m (29,530 ft) were used in Reference 6. A somewhat higher

maximum altitude of 40,000 feet above range floor is given in Reference 5, and altitudes of 55,000 to

60,000 feet are given for the internal AIS equipment.8 The 9000 m (approximately 30,000 ft) altitude

was used in this analysis.

2Application for Equipment Frequency Allocation (DD Form 1494) for AN/TSQ-T4 Remote Stations and subsequent

Notes to Holders, J/F 12/4322, Washington, DC: MCEB, April 1975.3Application for Equipment Frequency Allocation (DD Form 1494) for AN/TSQ-T4 Up Link and subsequent Notes to

Holders, J/F 12/4323, Washington, DC: MCEB, April 1975.4Application for Equipment Frequency Allocation (DD Form 1494) for TACTS,ACMI AIS Pods and subsequent Notes

to Holders, J/F 12/4324/2, Washington, DC: Naval Air Systems Command, May 1987.5Fred Williar, Naval Air Systems Command, e-mail to Allan Baker, JSC/IITRI, Subject: More TACTS Data, Patuxent

River NAS, MD, September 27, 2000.6Wayne Wamback, The Potential for Interference Between IMT-2000 Systems and U.S. DoD Systems Operating in the

Frequency Band 1755-1850 MHz, Annex 2, Alexandria, VA: AFFMA, 28 February 2000.7James E. Keeler, AAC/WMRR, e-mail to J. Don Simmons, Civ AAC/WMRR, Subject, DoD Forms for 1755 – 1850

MHz IMT-2000 Study, September 13, 2000.8Fred Williar, Naval Air Systems Command, e-mail to Allan Baker, JSC/IITRI, Subject: TACTS AIS Data, Patuxent

River NAS, MD, September 27, 2000.

IMT 2000 Assessment

E-3

Table E-1. TACTS/ACMI Transmitter CharacteristicsTransmitter

Characteris-ticTIS

MasterTIS

RemoteTIS

UplinkAIS

Downlink(Pod)a

AISDownlink(Internal)d

Power (W) 20 1 or 5b 5 c 20 10-15 (min)e

Modulation Type FSK,PM FSK,PM FSK,PM FSK,PM FSK,PMModulation

Indices0.9,0.3,0.3 0.9,0.3,0.3 9,3,3 9,3,3 8.2,2.7,2.7

CarrierDeviation (FSK)

± 74.4 kHz ± 74.4 kHz ± 74.4 kHz ± 74.4 kHz ± 74.4 kHz

Data Rate(kbps)

198 198 198 198 198

Widest EmissionBandwidth

(MHz)-3 dB 0.6 0.6 3.0 2.0 3.0

-20 dB 0.8 0.8 7.0 8.0 7.0-60 dB 2.1 2.1 12.0 12.0 12.0

HarmonicAttenuation (dB)

70 70 70 85 85

SpuriousAttenuation (dB)

70 70 70 70 70

aThe calibration transponder at the master station is electronically identical to the AIS pod.bDepends on manufacturer. Cubic Corp. uses 1 W, ADT uses 5 W (Ref. 5).c20 W at Tyndall ACMI and Yukon MDS ranges (Ref. 5).dData consolidated from Ref. 8.e15 W applies to AISI(K) (Ref. 8).

IMT-2000 Assessment

E-4

Table E-2. TACTS/ACMI Receiver CharacteristicsReceiver

Characteris-ticTIS

MasterTIS

RemoteTIS

DownlinkAISa

(Pod)AIS

(Internal)d

Sensitivity(dBm)

-95(BER =1x10-5)

-95(BER =1x10-5)

-95(BER =1x10-5)

-99(10 dB S/N)

(BER =1x10-5)

-95 dBm(100%

response), -99dBm (50%response)

Noise Levele

(dBm)-110 -110 -110 -111 -111

IF Bandwidthb

(MHz)-3 dB 1.5 1.5 1.5 1.2 1.2-20 dB 5.0 5.0 5.0 3.0 3.0-60 dB 12.0 12.0 12.0 8.0 8.0

ReceiverSelectivityc

(MHz)-3 dB 1.5 1.5 1.5 1.2 1.2-20 dB 2.9 2.9 2.9 3.0 3.0

-60 dB 7.4 7.4 7.4 6.8 6.8SpuriousResponse

(dB)

60 60 85 85 85

aThe calibration transponder at the master station is electronically identical to the AIS pod.bSecond IF bandwidthcBandwidth of combined first and second IF stages.dData consolidated from Ref. 8.eCalculated using 2.7 dB noise figure, from Ref. 5.

IMT 2000 Assessment

E-5

Table E-3. TACTS/ACMI Antenna CharacteristicsAntenna

CharacteristicTIS

MasterTIS

RemoteTIS

Uplink/Downlink

AIS(Pod)

AIS(Internal)

Type Parabolic(DipoleArrays)/Broad

Beamwidth

Parabolic CrossedDipoleArray

Dipole Dipole

Gain (dBi) 28,24,20d/14.5

26 3.0 0 0

Polarization V & H V,H RHCP RHCP RHCPHeight (ft) 75

(300 max)e100-150 160

(100-150)e30,000a,c 55,000-

60,000a,b

aMaximum altitude above mean sea levelbFrom Reference 8.cReference 5 gives a range of 10,000 to 30,000 ft. This reference also states that the TIS isspecified to track aircraft within altitudes of 500 ft. to 40,000 ft above the range floor.dDifferent values are given. The 20 dB value is given in Reference 1. Although a broadbeamwidth is usually desired, the antenna gain may depend on the installation.eAntenna height is site-dependent.

Table E-4. TACTS/ACMI Frequencies and UsageType of Link Frequencies (MHz)

Master-to-Remote 1768 or 1769AIS-to-Remote (Downlink) 1788 “A” Pod or 1778 “B” Pod

Remote-to-Master 1797, 1802, 1807, 1812, 1817, 1822Remote-to-AIS (Uplink) 1840 “A” Pod or 1830 “B” Pod

E.1.2 JTCTS Characteristics

E.1.2.1 System Characteristics

Tables E-5, E-6, and E-7 contain characteristics of the JTCTS. Characteristics were obtained from the

frequency allocation application,9 SRI International reports10,11 and material from the system

9Application for Equipment Frequency Allocation (DD Form 1494) for Joint Tactical Combat Training System (JTCTS)

Instrumentation Data Network, (Stage 4), J/F 12/06999/2, Patuxent River, MD, NAWCAD, 10 July 1998.10

David Hanz, Results from Phase 1a of the GSM-1800/JTCTS Datalink Signal Compatibility Test Program, SpecialReport 10240-99-SR-110, Menlo Park, CA: SRI International, November 1999.

11US DoD Air Combat Training Systems Development Roadmap for Next Generation & Spectrum Compatibility Issues,

dated 12 January 2000. Briefing given by D. Hanz of SRI International, 11 September 2000.

IMT-2000 Assessment

E-6

manufacturer which was provided by SRI International12,13 The high-power mode of operation

(67.6 W) was assumed. The shaded boxes contain assumed values.

E.1.2.1.2 Operational Considerations

In Reference 6, ground-to-air separation distances of 78 and 35 km were used for both the

TACTS/ACMI and JTCTS analyses. These values correspond to 48.5 mi (42.1 nmi) and 21.75 mi (18.9

nmi) respectively. However, it is realized that for the JTCTS, the ground-to-air links are secondary and

tertiary links. The primary link is the air-to-air link, with a maximum distance of 150 nmi (278 km). A

separation distance of this magnitude plus a smaller one (78 km or approximately 50 mi) were used in

the analysis.

The maximum number of aircraft is stated to be 100 for JTCTS, according to discussions at a 25

September 2000 meeting with NAVAIR and SRI International personnel and to Reference 7. Typical

numbers of aircraft may be somewhat less. In this analysis, the effect of the number of aircraft flying at

a particular time was not considered.

Altitudes of 5000 m (16,400 ft) and 9000 m (29,530 ft) were used in Reference 6. Some of the material

provided for the TACTS system indicates that maximum altitudes may be higher (e.g., 40,000 to 60,000

feet). However, after coordination with JTCTS engineering and operational personnel, an altitude of

9000 m (approximately 30,000 ft) was used in both the TACTS and JTCTS parts of the analysis.

12

Raytheon Systems Company, JTCTS Data Link Overview, Slide Package, undated, attachment to D. Hanz, SRIInternational, e-mail to A. Baker, IITRI/JSC, September 25, 2000. Subject: Reference Material #1.

13 Dave Hanz, SRI International, e-mail to Allan Baker, IITRI/JSC, Subject: More Reference, 25 September 2000, with

attachment Raytheon Specification G644379 8 February 1996 CAGE Code 49956 Rev. A: 31 December 1996.

IMT 2000 Assessment

E-7

Table E-5. JTCTS Transmitter CharacteristicsTransmitter Characteristic Narrowband Wideband

Power (W) 7.6 or 67.6 7.6 or 67.6Tuning Frequencies are selectable from 1710-1850 MHz in 5-MHz

increments (1755-1850 MHz in US & P).Modulation Type OQPSK with DS spread spectrum, 16-ary orthogonal Walsh

signalingData Rate (kbps) 351.5625, 703.125, 1406.25 351.5625, 703.125, 1406.25Chip Rate (Mcps) 5.63 22.5

Protocol TDMA-100 ms frame,Primary IDN: 25 slots/frame

Secondary IDN: 10 slots/frameError Detection and Correction Reed-Solomon FEC

Short Data Slots: (116,100)Long Data Slots: (128,100)

Relay Slots: (56,40)Emission Bandwidth (MHz)

-3 dB 2.1 4.8-20 dB 5.63 22.5-60 dB 22.5 90

Harmonic Attenuation (dB)(2 & 3) 70 70Other 80 80

Spurious Attenuation (dB) 80 80

Table E-6. JTCTS Receiver CharacteristicsReceiver Characteristic

Sensitivity (dBm) -106.5 @ 14.1 dB Eb/No, 351.56 kb/s, RScoding

Noise Figure (dB) 4.5Receiver Noise Level, dBmb -114.0 (352.6 kbps), -111.0 (703 kbps), -108

dBm (1406 kbps)First IF Bandwidth (MHz) Narrowbandc Wideband

-3 dB 22.5 22.5-20 dB 45 45-60 dB 60 60

Implementation Losses (dB) 2Spurious Response (dB) 60

Image Rejection (dB) 100Intermediate Frequency (MHz) 400

aIt is expected that additional selectivity is present, at the second IF or basebandbIn bandwidth equal to the bit rate.cNo additional filtering is used for the narrowband mode.14

14

David Hanz, SRI International, e-mail to Allan Baker, IITRI/JSC, 9 October 2000, Subject: JTCTS Characteristics.

IMT-2000 Assessment

E-8

Table E-7. JTCTS Antenna CharacteristicsAntenna

CharacteristicInstrumentation Data

Link(Aircraft Fuselage

Mounted)

Instrumentation DataLink

(Aircraft PodMounted)

Ship-to-ShoreLink

Type ¼ λ monopole blade ½ λ crossed dipoles Stacked dipole arrayGain (dBi) 2 6 8

Polarization V H,V VHeight (ft) 30,000 30,000

E.2 POTENTIAL FOR INTERFERENCE FROM IMT-2000 INTO TACTS/ACMI

E.2.1 Interference from IMT-2000 into TACTS/ACMI Airborne Receivers

The calculation of aggregate IMT-2000 interference into the TACTS/ACMI and JTCTS airborne

receivers was done in a manner similar to that in Reference 6, which was based on the levels used in

Recommendation ITU-R M.687-2.15 Two training ranges were selected, Cherry Point MCAS, in the

eastern US, and Nellis AFB in the western US. Both training ranges were within LOS of at least one

major metropolitan area. For each training range, a point within the boundary of the flight area was

selected, and metropolitan areas within the radio LOS of this point were selected. The assumed aircraft

receiver altitude was 9000 m (approximately 30,000 ft), and the radio LOS was calculated to be

approximately 260 miles. For each city, the equivalent area was calculated, and the propagation loss

was calculated using the JSC Smooth Earth Model (SEM)16 with the modified free space option.

Antenna heights used were 40 m for the IMT-2000 base stations and 9000 m for the airborne receiver.

The total power at the airborne receiver was calculated using Equation E-1 (Adapted from Reference 6):

I(dBW/Hz) = ∑=

n

1i

Pd Pmi Dpl lpi (E-1)

where:

15

International Telecommunications Union, International Mobile Telecommunications-2000 (IMT-2000),Recommendation ITU-R M.687-2, 1997.

16 David Eppink and Wolf Kuebler, TIREM/SEM Handbook, ECAC-HDBK-93-076, Annapolis, MD: DoD ECAC,March 1994.

IMT 2000 Assessment

E-9

Pd = power density per square kilometer per Hertz generated by IMT-2000 stations in anurban environment. Given by Reference 15 as 38 µW/km2/Hz

Pmi = population of the ith visible metropolitan area, in millions

Dpl = average inverse population density, in km2 per million

lpi = path loss from the ith metropolitan area, equal to 10-L/10, where L is the path loss fromthe JSC Smooth Earth Model (SEM), in dB

Values of Pm used were the populations of the Ranally Metropolitan Areas, taken from the Rand

McNally Commercial Atlas and Marketing Guide.17 The values used are population estimates for 1

January 1999.

In Reference 6, the average population density was determined by averaging the population densities of

the metropolitan areas or central cities for eight world cities. The average ratio was calculated to be

144.2 km2/million.

As in Reference 6, a factor for environmental losses, 10 dB, was subtracted from the results of Equation

E-1. Use of a lesser value, such as 0 dB, was also considered.

The results of the calculations using Equation E-1 are given in Tables E-8 and E-9 for Nellis AFB and

Cherry Point, respectively.

Table E-8. Power Levels from Nearby Cities, Nellis AFB ACMI RangeDistanceCity

Miles kmPopulation

(MetroArea)(mil.)

Equiv.Area(km2)

Path Loss,dB

ReceivedPowerDensity

(dBW/Hz)Las Vegas,

NV58 93 1.2575 181.3 137 -158.6

LosAngeles,

CA

260 418.4 13.11 1890.5 169.7 -181.1

Bakers-field, CA

234 376.6 0.404 58.24 149.1 -175.6

Fresno, CA 253 407.1 0.726 104.7 159.7 -183.7Riverside,

CA234 376.6 1.536 221.5 149.1 -169.8

17

Rand McNally & Co., Rand McNally 2000 Commercial Atlas & Marketing Guide, 131st Edition, 2000, pp. 124-125.

IMT-2000 Assessment

E-10

The total power density is -158.2 dBW/Hz; with a 10 dB factor for environmental losses, it is -168.2

dBW/Hz.

Table E-9. Power Levels from Nearby Cities, Cherry Point MCASDistanceCity

Miles kmPopulation

(MetroArea)(mil.)

Equiv.Area(km2)

Path Loss,dB

ReceivedPowerDensity

(dBW/Hz)Richmond

VA200 322 .861 124.1 147.7 -171.0

Norfolk, VA 140 225 1.006 144.9 144.6 -167.2Newport

News, VA140 225 0.476 68.6 144.6 -170.4

Fayette-ville, NC

135 217 0.319 46.1 144.3 -171.9

Charlotte,NC

240 386 1.215 175.3 149.3 -171.1

Charleston,SC

240 386 0.4782 69.1 149.3 -175.1

Columbia,SC

260 418 0.4924 71.0 169.4 -195.1

Raleigh,NC

140 225 0.6733 97.1 144.6 -168.9

Durham,NC

140 225 0.3273 47.2 144.6 -172.1

The total power was calculated to be -161.4 dBW/Hz; with a 10 dB factor for environmental losses, it is

-171.4 dBW/Hz.

Results of the interference calculations are given in Table E-10 for TACTS/ACMI air-to-ground

separation distances of 35 and 78 km, for the aggregate interfering signal without environmental losses,

the interfering signal with 10 dB losses, and the interfering signal attenuated by 10 dB, with the 10 dB

loss factor. The 10 dB attenuation may approximate a situation where the IMT-2000 system is near the

beginning of its full-scale implementation.

The results in Table E-10 show that the TACTS link margins are degraded to -22 to -29 dB, with the full

aggregate interfering signal, with 10 dB of environmental losses. With 10 dB less interfering power

than predicted with the full operational implementation, link margins are still degraded to -12 dB at the

35 km TACTS transmitter-to-receiver separation distance and -19 dB at the 78-km separation distance.

Since a number of factors could cause the calculated numbers to be higher than those shown, the results

suggest that sharing in a full IMT-2000 environment is not feasible.

IMT 2000 Assessment

E-11

Table E-10. TACTS/ACMI Airborne Receiver Link Margins With and WithoutIMT-2000 Interference

Aircraft Altitude 9000 m 9000 mDistance from Ground

Transmitter78 km 35 km

Range Between A/C andGround Transmitter

78.52 km 36.14 km

Ground Transmitter Power 7 dBW 7 dBWTransmit Antenna Gain 0 dBi 0 dBi

Transmitter System Losses 2 dB 2 dBTransmitter Data Rate (198.4

kbps)53.0 dBHz 53.0 dBHz

Transmit Eb -48 dBW -48 dBWFree Space Path Loss

(1800 MHz)135.4 dB 128.7 dB

Airborne Receiver AntennaGain

0 dBi 0 dBi

Rx Noise (3 dB NF) -201 dBW/Hz -201 dBW/HzEb/No 17.6 dB 24.3 dB

Criterion(Eb/No for BER = 10-5)

13.35 dB 13.35 dB

Margin (No Interference) 4.2 dB 10.9 dBIo -158 dBW/Hz -158 dBW/Hz

Eb/(No + Io) -25.4 dB -18.7 dBDegraded Below Criterion 38.8 dB 32.1 dB

Io -168 dBW/Hz -168 dBW/HzEb/(No + Io) -15.4 dB -8.7 dB

Degraded Below Criterion 28.8 dB 22.1 dBIo -178 dBW/Hz -178 dBW/Hz

Eb/(No + Io) -5.4 dB 1.3 dBDegraded Below Criterion 18.8 dB 12.1 dB

Io -188 dBW/Hz -188 dBW/HzEb/(No + Io) 4.6 dB 11.3

Degraded Below Criterion 8.8 dB 2.1 dB

E.2.2 Interference from IMT-2000 into TACTS/ACMI Ground-Based

Receivers

To analyze interference from IMT-2000 into TACTS/ACMI ground-based receivers, the required

separation distance to preclude interference into a ground receiver from a single IMT-2000 base and

mobile transmitter was calculated. The IMT-2000 parameters used in the calculations are given in

Tables A-4 and A-5. The TACTS ground receiver and antenna parameters are given in Tables E-1, E-2,

and E-3.

IMT-2000 Assessment

E-12

As was assumed in Reference 6, TACTS/ACMI operations are link-margin limited. The volume of

space usable for flight training is determined by the available link margin. It was assumed that the

maximum range between ground-based and airborne equipment, which determines the maximum

aircraft-to-aircraft separation, cannot be reduced by more than ten percent due to interference from IMT-

2000 systems. This condition equates to an allowed degradation in the TACTS/ACMI link margin of

approximately 1 dB and an I/N of –6 dB. It is noted, as in Reference 6, that the full amount of

interference degradation is made available to IMT-2000, rather than only ten percent of the total

interference budget, as is often considered reasonable.

Interference between ground-based transmitters and receivers was calculated using Equation E-2:

I = PT + GT + GR – LP – LS – LSP – FDR (E-2)

where

I = interference power in receiver, in dBm

PT = transmitter power, in dBm

GT = transmitter antenna gain in direction of receiver, in dBi

GR = receiver antenna gain in direction of transmitter, in dBi

LP = propagation loss, in dB

LS = system losses, in dB

LSP = processing loss of interference in a spread spectrum receiver, in dB

FDR = frequency-dependent rejection, in dB.

The interference power I was set to a maximum allowable value, the interference threshold It, which is

set for the TACTS/ACMI receivers at 6 dB below the receiver noise level, and Equation E-2 was

rearranged to form Equation E-3:

LP = PT + GT + GR – LS – LSP – FDR – It (E-3)

where quantities are as previously defined.

The factor LSP, for a direct-sequence spread spectrum receiver such as those used for CDMA versions of

the IMT-2000, is given by Equation E-4:

LSP = 10 log (Rc/Rd) (E-4)

IMT 2000 Assessment

E-13

where:

Rc = chip rate of receiver, chips/s

Rd = data rate of system, bits/s.

Frequency dependent rejection (FDR) for the ontune cases considered here is given by Equation E-5:

FDR = 10 log (Bt/Br) for Bt > Br

0 for Bt ≤ Br (E-5)

where:

Bt = transmitter 3-dB emission bandwidth, in Hertz

Br = receiver bandwidth, in Hertz.

The receiver bandwidth for use in Equation E-5 was assumed equal to the chip rate, for CDMA IMT-

2000 receivers and other direct-sequence spread-spectrum receivers. For TDMA receivers, the receiver

bandwidth and bit rate were assumed equal for this analysis, at 30 kHz for the IS-136 and 176 kHz for

the GSM system, and the LSP term is not applicable.

The required separation distance to preclude interference was calculated using the required propagation

loss from Equation E-3 and the JSC Inverse Smooth Earth Model. Antenna heights used were 40 m and

1.5 m for the IMT-2000 base station and mobile transmitters respectively, and 30 m for the

TACTS/ACMI receivers. The required separation distances are given in Table E-11. The distances

shown are the maximum for all versions of the IMT-2000 listed in Tables A-4 and A-5. For one case,

the wideband CDMA, a FDR of 3 dB would lower the separation distances slightly. For the other three

IMT-2000 versions, the FDR is 0 dB. TACTS/ACMI antenna gain values of 26 dBi and 0 dBi were

used. The 26 dBi gain represents either the master or the remote station in a ground-to-ground

interaction. The 0 dBi gain represents the remote station used as a TIS uplink. It is expected that the 3

dBi gain shown in Table E-3 would be reduced by 3 dB for polarization differences between the right-

hand circular polarization of the TACTS/ACMI antenna and the linear polarization of the interfering

signal.

Table E-11. Distances, in km, from IMT-2000 Transmitters to Preclude Interference toTACTS/ACMI Ground-Based Receivers

IMT-2000 StationTACTS/ACMI Antenna Gain(dBi) Mobile Base

0 20.0 70.126 38.9 146.1

IMT-2000 Assessment

E-14

E.3 INTERFERENCE FROM TACTS/ACMI INTO IMT-2000 SYSTEMS

E.3.1 Interference from TACTS/ACMI Ground-Based Transmitters into IMT-

2000 System

Separation distances to be maintained by IMT-2000 receivers from TACTS/ACMI ground transmitters

to preclude interference were calculated using the path loss from Equation E-3 and the inverse SEM

propagation model. Parameters for the IMT-2000 receivers are taken from Tables A-4 and A-5 and

parameters for the TACTS/ACMI transmitters and antennas were taken from Tables E-1 and E-3. For

the IMT-2000 receiver interference criteria, the two values in Tables A-4 and A-5 were used, plus an

additional, higher value, corresponding to the desired signal 20 dB above the receiver sensitivity level.

It was felt that the two higher thresholds used would represent a range of realistic received signal levels.

Separation distances for each interference threshold and TACTS/ACMI transmitter-antenna combination

are given in Table E-12. For the highest interference threshold, only one value, the worst-case, was

calculated. Distances for the other IMT-2000 versions are expected to be slightly less, as was the case

for the lower thresholds.

For the narrowband TACTS signals, the Master Station (MS) and TIS ground-to-ground links, the

separation distances for the CDMA WB and NB IMT-2000 implementations are slightly smaller than for

the TDMA implementation. This is because the CDMA implementations offer some processing loss to

the narrowband TACTS signal, due to the correlation of the desired signal and subsequent narrowband

filtering in the receiver. The separation distances for both TDMA implementations were practically

identical.

IMT 2000 Assessment

E-15

Table E-12. Distances, in km, from TACTS/ACMI Ground-Based Transmitters to Preclude

Interference to IMT-2000 ReceiversIMT-2000 Station

Mobile BaseTACTS/ACMI Antenna Gain

and Tx PowerCDMA

WBCDMA

NBTDMA CDMA

WBCDMA

NBTDMA

IMT-2000 Interference Criterion I/N = -6 dBMS 26 dBi/20 W 46 48.4 50.7 132.1 157.9 180.3TIS 26 dBi/1 W 38.5 41.3 43.2 85.1 98.4 110G/A 0 dBi/5 W 25.2 25.9 26 63.2 63.9 64

IMT-2000 Interference Criterion for S = Sensitivity + 10 dBMS 26 dBi/20 W 36.9 39.8 41.8 80 90.8 101TIS 26 dBi/1 W 27.9 31.4 33.7 66 69.7 72.5G/A 0 dBi/5 W 11.9 12.7 12.8 49.2 50.1 50.2

IMT-2000 Interference Criterion for S = Sensitivity + 20 dBMS 26 dBi/20 W 35.3 74.6TIS 26 dBi/1 W 26.0 64.3G/A 0 dBi/5 W 5.7 39.1

E.3.2 Interference from TACTS/ACMI Airborne Transmitters into IMT-2000

System

The required separation distances between an airborne TACTS/ACMI transmitter (at 9000 m altitude)

and IMT-2000 base and mobile stations were calculated in a manner similar to those for the ground-

based ACTS transmitters. For each value of required path loss, the JSC inverse smooth-earth

propagation model was used to calculate the required separation distance. For the IMT-2000 base

stations, a 2.5-degree downtilt angle was assumed and a maximum antenna gain, at the horizon or above,

of 5 dBi was used in the analysis. Results of the calculations are shown in Table E-13. Because of the

relatively wide bandwidth of the AIS downlink signal, little processing gain is realized by the CDMA

implementations, and the separation distances for the three versions are not significantly different. The

required separation distances for the base stations approach LOS for the lowest interference threshold,

and they are in the neighborhood of 180 km for the middle interference threshold. These distances could

significantly reduce the area of IMT-2000 usage near TACTS/ACMI training ranges.

IMT-2000 Assessment

E-16

Table E-13. Required Separation Distances, in km, to Preclude Interference from TACTS/ACMIAirborne Transmitters into IMT-2000 Receivers

IMT-2000 StationMobile Base

CDMAWB

CDMANB

TDMA CDMAWB

CDMANB

TDMA

IMT-2000 Interference Criterion I/N = -6 dB318.9 320.1 322.7 404.4 405.4 405.5

IMT-2000 Interference Criterion for S = Sensitivity + 10 dB57.1 63.5 64.3 162.8 180.6 182.7

IMT-2000 Interference Criterion for S = Sensitivity + 20 dB14.7 16.9 17.1 47.8 53.2 53.9

E.4 POTENTIAL FOR INTERFERENCE FROM IMT-2000 INTO JTCTS

E.4.1 Interference from IMT-2000 into JTCTS Airborne Receivers

The JTCTS data link signal structure is 16-ary, orthogonal signaling, with 0.351, 0.703, and 1.406 Mbps

data rates combined with either 5.63 or 22.5 Mchips/s pseudorandom spreading codes. Symbol rates are

89.9, 175.8, and 351.5 ksps. The required Es/No, including Reed-Solomon forward error-correcting code

gain, is 11.0 dB.

Table E-14 contains the calculations of the JTCTS link margins for the aircraft altitude of 9000 m

(approximately 30,000 feet), and two separation distances, in the absence of interference. The first

separation distance, 78 km, is the same as used in the TACTS analysis. The second distance, 150 nmi

(277.8 km) represents the specified maximum separation distance for the JTCTS air-to-air link

(Reference 12), which is its primary communications link. In the absence of interference, link margins

vary, depending on the symbol rate, from 16 to 22 dB for the 78 km distance, and from 5 to 11 dB for

the 278 km distance.

It was assumed that the JTCTS was subjected to the same aggregate IMT-2000 interference levels as

those calculated earlier for the TACTS/ACMI systems. Table E-15 shows the received Es/(No + Io) and

resulting link margins in the presence of the aggregate IMT-2000 RF environment. With Io = -168

dBW/Hz, negative link margins of from –10 to –16 dB result, depending on the data rate, for the 78 km

distance. For the 150 nmi (278 km) separation, the link margins are 11 dB less, from –21 to –27 dB.

For a l0-dB lower aggregate interference level, expected to occur before a mature usage rate is

developed, negative link margins exist for all but the lowest symbol rate (87.9 ksps) at the 78 km

separation, and at all symbol rates at the 278 km separation.

IMT 2000 Assessment

E-17

Comparison of the results for the JTCTS and TACTS/ACMI systems show that the JTCTS link margins

are somewhat higher in the presence of interference, than are those of the TACTS/ACMI. However, the

effect is still such that, even with an incomplete buildup of the IMT-2000 environment, operation of the

systems at typical training ranges will be degraded.

Table E-14. JTCTS Airborne Receiver Link Margins Without IMT-2000 InterferenceAircraft Altitude 9000 m 9000 m

Distance from Tx 78 km 277.8 km (150 nmi)Transmitter Power 18.3 dBW 18.3 dBW

Transmit Antenna Gain 2 dBi 2 dBiTx System Losses 2 dB 2 dB

Transmit Symbol Rate87.9 ksps 49.5 dBHz 49.5 dBHz

175.8 ksps 52.5 dBHz 52.5 dBHz351.6 ksps 55.5 dBHz 55.5 dBHz

Transmit Energy per Symbol87.9 ksps -31.2 dBW -31.2 dBW

175.8 ksps -34.2 dBW -34.2 dBW351.6 ksps -37.2 dBW -37.2 dBW

Free Space Path Loss (1800 MHz) 135.4 dB 146.4 dBAirborne Receiver Antenna Gain 2 dBi 2 dBi

Received Es

87.9 ksps -164.6 dBW -175.6 dBW175.8 ksps -167.6 dBW -178.6 dBW351.6 ksps -170.6 dBW -181.6 dBW

Rx No (4.5 dB NF) -199.5 dBW/Hz -199.5 dBW/HzEs/No

87.9 ksps 34.9 23.9175.8 ksps 31.9 20.0351.6 ksps 28.9 17.9

Implementation Losses 2.0 dB 2.0 dBRequired Es/No 11.0 dB 11.0 dB

Margin87.9 ksps 21.9 dB 10.9 dB

175.8 ksps 18.9 dB 7.9 dB351.6 ksps 15.9 dB 4.9 dB

IMT-2000 Assessment

E-18

Table E-15. JTCTS Airborne Receiver Link Margins and Degradation Due to IMT-2000Aircraft Altitude 9000 m 9000 m

Distance from Transmitter 78 km 277.8 kmReceived Es/No

87.9 ksps -164.6 dB -175.6 dB175.8 ksps -167.6 dB -178.6 dB351.6 ksps -170.6 dB -181.6 dB

Io -158 dBW/Hz -158 dBW/HzEs/(No + Io)87.9 ksps -6.6 dB -17.6 dB175.8 ksps -9.6 dB -20.6 dB351.6 ksps -12.6 dB -23.6 dB

Margin87.9 ksps -19.6 dB -30.6 dB175.8 ksps -22.6 dB -33.6 dB351.6 ksps -25.6 dB -36.6 dB

Io -168 dBW/Hz -168 dBW/HzEs/(No + Io)87.9 ksps 3.4 dB -7.6 dB175.8 ksps 0.4 dB -10.6 dB351.6 ksps -2.6 dB -13.6 dB

Margin87.9 ksps -9.6 dB -20.6 dB175.8 ksps -12.6 dB -23.6 dB351.6 ksps -15.6 dB -26.6 dB

Io -178 dBW/Hz -178 dBW/HzEs/(No + Io)87.9 ksps 13.4 dB 2.4 dB175.8 ksps 10.4 dB -0.6 dB351.6 ksps 7.4 dB -3.6 dB

Margin87.9 ksps 0.4 dB -10.6 dB175.8 ksps -2.6 dB -13.6 dB351.6 ksps -5.6 dB -16.6 dB

Io -188 dBW/Hz -188 dBW/HzEs/(No + Io)87.9 ksps 23.4 dB 12.4 dB175.8 ksps 20.4 dB 9.4 dB351.6 ksps 17.4 dB 6.4 dB

Margin87.9 ksps 10.4 dB -0.6dB175.8 ksps 7.4 dB -3.6 dB351.6 ksps 4.4 dB -6.6 dB

E.4.2 Interference from IMT-2000 into JTCTS Ground-Based Receivers

As was done for the TACTS/ACMI, it was assumed for the JTCTS that the maximum range between

ground and air stations (which in turn determines the maximum aircraft-to-aircraft separation) cannot be

IMT 2000 Assessment

E-19

reduced by more than about 10 percent due to interference from IMT-2000 systems. This condition

equates to an allowed degradation in the JTCTS link margin of approximately 1 dB and an interference-

to-noise power ratio criterion of –6 dB. It again is noted that the full amount of interference

degradation is made available to IMT-2000, rather than apportioning only 10 percent of the total

interference budget to this system, as is sometimes considered reasonable. Although a high (26 dBi)

antenna gain was not given in the JTCTS system description, it was assumed that an antenna of this type

could be used in a tertiary, or ground-to-ground, link.

All IMT-2000 transmitters considered were narrower in bandwidth than the narrower-bandwidth JTCTS

chip rate. A processing loss equal to the ratio of the chip rate to the data rate was applied to the

interfering signal level, as described earlier. For each chip rate, the separation was the same for each

data rate considered. This is due to the processing loss compensating for the change in noise level. The

processing loss is proportional to the data rate, while the noise power, and hence the interference

threshold, is inversely proportional to the data rate. See Table E-16.

Table E-16. Separation Distances, in km, from JTCTS Ground Receivers to Preclude Interferencefrom IMT-2000 Transmitters

IMT-2000 StationJTCTS Antenna Gain,(dBi)

JTCTSReceiverChip Rate(MChips/

s)

Data Rate, Mb/sMobile Base

0.3516 13.0 65.45.631.406 13.0 65.40.3516 8.1 58.7

0

22.51.406 8.1 58.70.3516 33.8 117.35.631.406 33.8 117.30.3516 29.6 89.5

26

22.51.406 29.6 89.5

E.5 INTERFERENCE FROM JTCTS INTO IMT-2000 SYSTEMS

E.5.1 Interference from JTCTS Ground-Based Transmitters into IMT-2000

System

Separation distances which may need to be maintained by IMT-2000 receivers to preclude interference

from JTCTS ground transmitters were calculated in a manner similar to those corresponding distances

for the TACTS/ACMI ground transmitters. The JSC inverse SEM propagation model was used, with

IMT-2000 Assessment

E-20

the JTCTS characteristics of Tables E-5 and E-7 and the IMT-2000 characteristics of Tables A-4 and

A-5. Separation distances were calculated for both the narrowband and wideband JTCTS signal, and

each of the four IMT-2000 variations considered, for both mobile and base stations. Results are given in

Tables E-17 and E-18. In Table E-17, the separation distances for each version of the IMT-2000,

against the wideband JTCTS signal, were the same. In Table E-18, the wideband CDMA version gave

slightly more processing loss to the narrowband JTCTS signal, resulting in slightly smaller separation

distances, when compared to the other versions, whose separation distances were identical.

Table E-17. Distances, in km, from JTCTS Wideband Ground-Based Transmitters to PrecludeInterference to IMT-2000 Receivers

IMT-2000 StationJTCTS Antenna Gain (dBi)Mobile Base

IMT-2000 Interference Criterion I/N = -6 dB0 32.1 71.312 40.3 93.426 48.1 154.2

IMT-2000 Interference Criterion for S = Sensitivity + 10 dB0 20.8 58.612 30.2 68.526 39.5 89.2

IMT-2000 Interference Criterion for S = Sensitivity + 20 dB0 11.7 48.912 22.1 60.026 32.8 71.4

Table E-18. Distances, in km, from JTCTS Narrowband Ground-Based Transmitters to PrecludeInterference to IMT-2000 Receivers

IMT-2000 StationMobile Base

JTCTS Antenna Gain (dBi)

WB CDMA Others WB CDMA Others

IMT-2000 Interference Criterion I/N = -6 dB0 33.5 35.2 72.3 74.412 41.1 42.5 97.1 105.726 48.7 50.6 161.7 178.8

IMT-2000 Interference Criterion for S = Sensitivity + 10 dB0 21.8 23.9 59.6 61.812 31.1 32.8 69.4 71.526 40.2 41.7 92.5 100.4

IMT-2000 Interference Criterion for S = Sensitivity + 20 dB

0 12.6 14.8 50.0 52.412 23.1 25.1 60.9 63.026 33.5 35.2 72.3 74.4

IMT 2000 Assessment

E-21

E.5.2 Interference from JTCTS Airborne Transmitters into IMT-2000 System

The interference from airborne JTCTS transmitters into IMT-2000 receivers was calculated using the

same approach and path loss model as was done in a preceding section for the TACTS/ACMI system.

As in the preceding section, results are given for both narrowband and wideband JTCTS waveforms.

Results are given in Tables E-19 and E-20. Again, for the wideband JTCTS waveform, distances are

equal for all IMT-2000 versions, while for the narrowband JTCTS waveform, the wideband CDMA

IMT-2000 implementation results in a slightly lower separation distance.

Tables E-19 and E-20 show that the required separation distances are quite high (100 to 400 km), even

for the higher interference thresholds. They are higher than those shown for the TACTS/ACMI

transmitters, primarily because of the higher EIRP of the JTCTS equipment. Depending on the

interference criterion used, coordination to line of sight distances may be necessary to avoid interference

from the airborne system to the IMT-2000 receivers.

Table E-19. Required Separation Distances, in km, to Preclude Interference from JTCTSWideband Airborne Transmitters into IMT-2000 Receivers

IMT-2000 StationMobile Base

CDMAWB

CDMANB

TDMA CDMAWB

CDMANB

TDMA

IMT-2000 Interference Criterion I/N = -6 dB343.6 343.6 343.6 415.9 415.9 415.9

IMT-2000 Interference Criterion for S = Sensitivity + 10 dB187.0 187.0 187.0 399.7 399.7 399.7

IMT-2000 Interference Criterion for S = Sensitivity + 20 dB55.2 55.2 55.2 157.3 157.3 157.3

Table E-20. Required Separation Distances, in km, to Preclude Interference from JTCTSNarrowband Airborne Transmitters into IMT-2000 Receivers

IMT-2000 StationMobile Base

CDMAWB

CDMANB

TDMA CDMAWB

CDMANB

TDMA

IMT-2000 Interference Criterion I/N = -6 dB346 351.4 351.4 417 420 420

IMT-2000 Interference Criterion for S = Sensitivity + 10 dB212 283.7 283.7 400 402 402

IMT-2000 Interference Criterion for S = Sensitivity + 20 dB62.8 84.1 84.1 179 238 238

IMT-2000 Assessment

E-22

E.6 BAND SEGMENTING PLANS

The analysis described in the previous sections assumed no separation in frequency between the IMT-

2000 and ACTS systems. If the present band is segmented, with separate but adjacent segments

allocated separately to ACTS and IMT-2000 systems, the effect of frequency separation between the

two systems becomes of importance.

Two proposed methods for operating within the 1755 to 1850 MHz band were examined briefly, and the

feasibility of satisfactory operation of the ACTS and IMT-2000 equipment was assessed.

In the first plan, the 1755-1805 MHz portion of the band remains allocated to ACTS. The rest of the

band is allocated to IMT-2000 systems. In the second plan, ACTS and IMT-2000 are allowed to operate

in the present band. The ACTS systems operate as they presently do, and the IMT-2000 systems must

coordinate in the areas where ACTS operates and where interference is a possibility.

E.6.1 Band Segmenting Plan 1

Under plan 1, the TACTS/ACMI would lose six of the 11 frequencies now available to it across the

1768 to 1840 MHz range. It would lose use of the 1840 MHz (A) or 1830 MHz (B) air-to-ground link

transmit frequencies, and four of the six frequencies (1807, 1812, 1817, and 1822 MHz) used for

transmitting from the remote ground transmitters to the master receiver. Typically, the TACTS/ACMI

uses eight or more frequencies for its necessary functions. Loss of all but the 1755-1805 MHz portion

of the band does not appear feasible for satisfactory operation of the present TACTS/ACMI system.

The JTCTS normally uses one to three frequencies between 1710 and 1850 MHz. One frequency is

used for air-to-air communications, the primary link. A second frequency is often used for the

secondary link, for ground-to-air communications. The third frequency is used for a tertiary data link

for ground to ground communications. This link is not always used.

In conversations with JTCTS engineers at SRI International, it has been stated that it may be possible for

the JTCTS to operate with two 22.5 MHz channels separated by 5 MHz at the –20 dB points of the

spectrum. The total occupied bandwidth would be approximately 22.5 x 2 + 5 = 50 MHz. The third

frequency, for the tertiary link, could be reassigned to a different, probably a higher, band. It may be

possible that the two channels can operate without mutual interference, as has been stated. However,

the effect of JTCTS interactions with IMT-2000 equipment near the edges of the band must also be

investigated. A preliminary assessment of the effects of frequency separation was made by generating

IMT 2000 Assessment

E-23

frequency-distance curves for JTCTS-to-IMT-2000 and IMT-2000-to-JTCTS interactions. The curves

generated are for wideband CDMA and wideband JTCTS versions. The middle CDMA interference

threshold was used, corresponding to a desired signal 10 dB above sensitivity. These curves are given

as Figures E-1 and E-2. Although conservative interference thresholds were used in generating these

curves, they show that, at the band edges, 11.25 MHz from the JTCTS wideband center frequency,

significant separation distances are needed to avoid interference. Further investigations of these

interactions would be necessary to determine the feasibility of this band segmenting plan.

F -D C U R V E -IM T -2 00 0 B A S E T O JT C T S A IR

0

5 0

1 0 0

1 5 0

2 0 0

2 5 0

3 0 0

3 5 0

4 0 0

4 5 0

5 0 0

0 1 0 2 0 3 0 4 0 5 0 6 0 7 0 8 0 9 0

F re q u e n c y S e p a ra tio n , M H z

Dis

tan

ce, k

m

Figure E-1. Frequency-Distance Curve for JTCTS Airborne to IMT-2000 Interaction

IMT-2000 Assessment

E-24

F-D CURVE-JTCTS AIR TO IMT-2000 BASE

0

50

100

150

200

250

300

350

400

450

0 5 10 15 20 25 30 35 40 45

Frequency Separation, MHz

Dis

tan

ce, k

m

Figure E-2. Frequency-Distance Curve for IMT-2000 to JTCTS Airborne Interaction

E.6.2 Band Segmenting Plan 2

In plan 2, which involves coordination within the same band, IMT-2000 systems would be forced to

coordinate their operation in areas where present ACTS systems operate and interference is a possibility.

In the first segment of the band to be made available, 1710 to 1755 MHz, no TACTS/ACMI frequencies

exist, and it may be possible for JTCTS to avoid this range. For the other segments (1755 to 1780 and

1780 to 1790 MHz), airborne and ground-based TACTS/ACMI frequencies are used. The results of the

previous sharing analysis show that, for the airborne ACTS transmitters, coordination distances to avoid

interference to an IMT-2000 receiver are sometimes at line-of-sight distances (400 km for 9000 m

altitude). Distances needed to avoid interference from aggregate IMT-2000 environments to an airborne

ACTS receiver are more difficult to calculate. However, with a single metropolitan area the size of Las

Vegas, NV, and ignoring the effects of other cities, preliminary calculations indicate that separation

distances of the same magnitude or larger may be needed.

IMT 2000 Assessment

E-25

E.6.3 Band Segmenting Conclusions

Interference problems exist in implementing both segmenting plans 1 and 2. With plan 1, operation of

the present TACTS/ACMI is not feasible. Operation of JTCTS, with the tertiary data link assigned to a

different band, may be feasible. However, further investigation is needed to verify this conclusion.

E.7 CONCLUSIONS

Because of the large separation distances needed to avoid interference from airborne ACTS transmitters

to IMT-2000 receivers, and because of the effect of the aggregate IMT-2000 ground environment on the

link margins of the airborne ACTS receivers, sharing of the two systems, without frequency separation,

does not appear feasible.

Interference between airborne ACTS transmitters and IMT-2000 receivers and between the aggregate

IMT-2000 environment and ACTS airborne receivers seem to be the worst, or most limiting, cases, for

band sharing.

A 10 dB reduction of aggregate interference power, as might be associated with an incomplete buildup

of a mature IMT-2000 environment, still results in negative link margins for TACTS/ACMI and JTCTS

airborne receivers.

For ground-to-ground interactions, separation distances to avoid interference appear to be of the same

order of magnitude for ACTS-to-IMT-2000 and IMT-2000-to-ACTS interactions. Effects on system

operation depend on interference thresholds used and the location of the ACTS ground equipment.

Of the band-segmenting plans proposed, plan 1 involves use of only the 1755-1805 portion of the band.

Operation of the TACTS/ACMI does not appear feasible with this plan. Operation of the JTCTS may be

possible with reassignment of one of the three channels. Interactions of JTCTS with IMT-2000

equipment in adjacent bands need to be investigated further before feasibility of this option can be

demonstrated.

Segmentation plan 2 involves coordination of IMT-2000 operations in regions where ACTS systems

presently operate and interference is possible. For the portions of the band above 1755 MHz,

preliminary analysis, as discussed in this report, indicates that, because of the use of airborne ACTS

transmitters and receivers, coordination distances from flight areas may exceed 400 km, making this

plan difficult to implement.

IMT-2000 Assessment

E-26

E.8 MITIGATION TECHNIQUES

Possible methods to mitigate interference between IMT-2000 and ACTS equipment include the

following:

• Coordination of antenna orientation of IMT-2000 base stations with the location of the training

ranges. The mainbeams of the IMT-2000 antennas should not point in the direction of training

range ground stations or of major flight activity, and the IMT-2000 base stations should not be

illuminated by the mainbeams of high-gain ACTS ground station antennas.

• Coordination of training range aircraft training schedules with IMT-2000 operations, such that

IMT-2000 power levels, frequencies, or antenna orientations could be adjusted to avoid mutual

interference.

• Use of polarization diversity between IMT-2000 base stations and ACTS equipment, to reduce

interference levels for mainbeam-to-mainbeam interactions between IMT-2000 and ACTS

equipment.